Masud Mansuripur

Interests

Teaching

1) Classical Electrodynamics; 2) Mathematical Methods in Optics & Photonics; 3) Fourier Optics; 4) Information Theory; 5) Linear System Theory.

Research

1) Classical Optics; 2) Classical Theories of Electromagnetism and Electrodynamics; 3) Problems Associated with Radiation Pressure and Photon Momentum; 4) Optical Data Storage; 4) Macromolecular Data Storage; 5) Thin Film Optics.

Courses

Scholarly Contributions

Books

• Mansuripur, M. (2017). Field, Force, Energy and Momentum in Classical Electrodynamics. Sharjah, United Arab Emirates: Bentham e-books.
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  The classical theory of electrodynamics is based on Maxwell's equations and the Lorentz law of force. This book begins with a detailed analysis of these equations, and proceeds to examine their far-reaching consequences. The traditional approach to electrodynamics treats the "microscopic" equations of Maxwell as fundamental, with electric charge and electric current as the sole sources of the electric and magnetic fields. Subsequently, polarization and magnetization are introduced into Maxwell's equations to account for the observed behavior of material media. The augmented equations, known as Maxwell's "macroscopic" equations, are considered useful for practical applications, but ultimately reducible to the more fundamental "microscopic" equations. In contrast, the present book takes Maxwell's "macroscopic" equations as the foundation of classical electrodynamics, and treats electrical charge, electrical current, polarization, and magnetization as the basic constituents of material media. These constituents not only produce the electromagnetic fields, but also interact with these fields and exchange energy and momentum with them. The laws that govern the distribution of energy and momentum in space-time are introduced and discussed in great detail. Interactions of electromagnetic fields with matter involve exchanges of energy with electrical currents, with polarization, and with magnetization, and also exchanges of linear and angular momenta via electromagnetic force and torque exerted on the aforementioned constituents of matter. Throughout the book, a large number of examples demonstrate the solution of Maxwell's equations in diverse situations, and examine the flow of energy and momentum as well as the distribution of force and torque throughout the matter-field systems under consideration.

Journals/Publications

• Mansuripur, M. (2020). A Tutorial on the Classical Theories of Electromagnetic Scattering and Diffraction,. Nanophotonics.
• Mansuripur, M. (2020). Ubiquity of Fourier transformation in optical sciences. Applied optics, 59(22), G47--G63.
• Mansuripur, M., & Jakobsen, P. K. (2020). Electromagnetic radiation and the self torque of an oscillating magnetic dipole. Proceedings of SPIE.
• Mansuripur, M., & Jakobsen, P. K. (2020). Electromagnetic radiation and the self-field of a spherical dipole oscillator. American Journal of Physics, 88(9), 693--703.
• Mansuripur, M. (2019). Absorption and Stimulated Emission by a Thin Slab Obeying the Lorentz Oscillator Model. Japanese Journal of Applied Physics, 58(SK), SKKB02. doi:10.7567/1347-4065/ab2cc6
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  In his celebrated 1916-17 papers in which he proposed the A and B coefficients for the spontaneous and stimulated emission of energy quanta from excited atoms, Einstein conjectured that stimulated emission involves the release of individual quanta (later dubbed "photons") along the direction of an incident photon with the same energy, momentum, phase, and polarization state as that of the incident photon. According to classical electrodynamics, of course, an oscillating dipole must radiate an azimuthally symmetric electromagnetic field around its axis of oscillation. Nevertheless, Einstein suggested that the release of stored energy from excited atoms in the form of discrete quanta (photons) must be directional, and that, in the case of stimulated emission, the direction of the emitted photon must coincide with that of the incident photon. The goal of the present paper is to show that some of the prominent features of absorption and stimulated emission emerge from Maxwellian electrodynamics in conjunction with the simple mass-and-spring model of an atom known as the Lorentz oscillator model.
• Mansuripur, M., & Jakobsen, P. K. (2019). An approach to constructing super oscillatory functions. Journal of Physics A, 52(30), 305202. doi:10.1088/1751-8121/ab27de
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  A recipe is presented for constructing band-limited superoscillating functions that exhibit arbitrarily high frequencies over arbitrarily long intervals.
• Mansuripur, M. (2017). Electromagnetic Angular Momentum. Journal of Optics, 19, 10-11.
• Mansuripur, M. (2017). Electromagnetic Force and Momentum. Journal of Optics, 19, 8-9.
• Mansuripur, M. (2017). Force, Torque, Linear Momentum, and Angular Momentum in Classical Electrodynamics. Applied Physics A, 123, 1-11.
• Mansuripur, M. (2017). Leaky Modes of Solid Dielectric Spheres. Physical Review A, 96, 1-14.
• Mansuripur, M. (2017). Nature of the electromagnetic force between classical magnetic dipoles. Proceedings of SPIE, 10357, 1-6. doi:10.1117/12.2273216
• Mansuripur, M. (2017). Optical Angular Momentum in Classical Electrodynamics. Physica Scripta, 92, 1-9.
• Mansuripur, M. (2017). Thermodynamics of Radiation Pressure and Photon Momentum. Proceedings of SPIE, 10347, 1-20. doi:10.1117/12.2274589
• Mansuripur, M. (2016). Comment on Jackson’s analysis of electric charge quantization due to interaction with Dirac’s magnetic monopole. Scientia Iranica, Transactions D: Computer Science & Engineering and Electrical Engineering, 23(6), 2874-2880.
• Mansuripur, M. (2016). Hybrid transparent conductive electrodes with copper nanowires embedded in a zinc oxide matrix and protected by reduced graphene oxide platelets,. Journal of Applied Physics.
• Mansuripur, M. (2016). Light-Matter Interaction: Conversion of Optical Energy and Momentum to Mechanical Vibrations and Phonons. Quantum Sensing and Nano Electronics and Photonics XIII, edited by M. Razeghi, G.J. Brown, and J.S. Lewis, Proceedings of SPIE, 9755, 975521~1-34.
• Mansuripur, M. (2016). Sol-gel deposited aluminum-doped and gallium-doped zinc oxide thin-film transparent conductive electrodes with a protective coating of reduced graphene oxide. SPIE Journal of Nanophotonics.
• Mansuripur, M. (2017). "Electromagnetic Angular Momentum", Section 5 of Roadmap on Structured Light. Journal of Optics, 19, 013001~10-11.
• Mansuripur, M. (2017). "Electromagnetic Force and Momentum" Section 4 of Roadmap on Structured Light. Journal of Optics, 19, 013001~8-9.
• Mansuripur, M., Kolesik, M., & Jakobsen, P. (2016). Leaky Modes of Dielectric Cavities. Spintronics IX, edited by H.-J. Drouhin, J.-E. Wegrowe, and M. Razeghi, Proceedings of SPIE, 9931, 99310B~1:20.
• Zhu, Z., Mankowski, T., Shikoh, A. S., Touat, F., Benammar, M. A., Mansuripur, M., & Falco, C. M. (2016). Ultra-high aspect ratio copper nanowires as transparent conductive electrodes for dye sensitized solar cells. Thin Films for Solar and Energy Technology VIII, edited by M.J. Heben and M.M. Al-Jassim, Proceedings of SPIE, 9936, 993603~1:8.
• Mansuripur, M. (2015). Reply to ‘Comment on ‘Deducing radiation pressure on a submerged mirror from the Doppler shift’. Physical Review A, 92.
• Mansuripur, M. (2015). Ultrahigh Aspect Ratio Copper-Nanowire-Based Hybrid Transparent Conductive Electrodes with PEDOT:PSS and Reduced Graphene Oxide Exhibiting Reduced Surface Roughness and Improved Stability. ACS Applied Materials & Interfaces, 7(30), 16223-16230.
• Spavieri, G., & Mansuripur, M. (2015). Origin of the Spin-Orbit Interaction. Physica Scripta, 90.
• Lau, P. C., Norwood, R. A., Mansuripur, M., & Peyghambarian, N. N. (2014). An effective nanosensor for organic molecules based on water-soluble mercaptopropionic acid-capped CdTe nanocrystals with potential application in high-throughput screening and high-resolution optical microscopy. Biomedical Optics Express, 5, 2420-2434.
• Mansuripur, M. (2014). Advances in macromolecular data storage. Proceedings of SPIE, 9201. doi:10.1117/12.2060549
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  We propose to develop a new method of information storage to replace magnetic hard disk drives and other instruments of secondary/backup data storage. The proposed method stores petabytes of user-data in a sugar cube (1 cm3), and can read/write that information at hundreds of megabits/sec. Digital information is recorded and stored in the form of a long macromolecule consisting of at least two bases, 𝐴 and 𝐵. (This would be similar to DNA strands constructed from the four nucleic acids 𝐺, 𝐶, 𝐴, 𝑇.) The macromolecules initially enter the system as blank slates. A macromolecule with, say, 10,000 identical bases in the form of 𝐴𝐴𝐴𝐴𝐴. . . . 𝐴𝐴𝐴 may be used to record a kilobyte block of user-data (including modulation and error-correction coding), although, in this blank state, it can only represent the null sequence 00000....000. Suppose this blank string of 𝐴’s is dragged before an atomically-sharp needle of a scanning tunneling microscope (STM). When electric pulses are applied to the needle in accordance with the sequence of 0s and 1s of a 1 𝑘𝐵 block of user-data, selected 𝐴 molecules will be transformed into 𝐵 molecules (e.g., a fraction of 𝐴 will be broken off and discarded). The resulting string now encodes the user-data in the form of 𝐴𝐴𝐵𝐴𝐵𝐵𝐴. . . 𝐵𝐴𝐵. The same STM needle can subsequently read the recorded information, as 𝐴 and 𝐵 would produce different electric signals when the strand passes under the needle. The macromolecule now represents a data block to be stored in a “parking lot” within the sugar cube, and later brought to a read station on demand. Millions of parking spots and thousands of Read/Write stations may be integrated within the micro-fabricated sugar cube, thus providing access to petabytes of user-data in a scheme that benefits from the massive parallelism of thousands of Read/Write stations within the same three-dimensionally micro-structured device.
• Mansuripur, M. (2014). The Lorentz force law and its connections to hidden momentum, the Einstein-Laub force, and the Aharonov-Casher effect. IEEE Transactions on Magnetics, 50, 1300110~1:10.
• Mansuripur, T. S., & Mansuripur, M. (2014). Fresnel reflection from a cavity with net roundtrip gain. Applied Physics Letters, 104(12).
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  Abstract: A planewave incident on an active etalon with net roundtrip gain may be expected to diverge in field amplitude, yet applying the Fresnel formalism to Maxwell's equations admits a convergent solution. We describe this solution mathematically and provide additional insight by demonstrating the response of such a cavity to an incident beam of light. Cavities with net roundtrip gain have often been overlooked in the literature, and a clear understanding of their behavior yields insight to negative refraction in nonmagnetic media, a duality between loss and gain, amplified total internal reflection, and the negative-index lens. © 2014 AIP Publishing LLC.
• Lau, P. C., Norwood, R. A., Mansuripur, M., & Peyghambarian, N. (2013). An effective and simple oxygen nanosensor made from MPA-capped water soluble CdTe nanocrystals. Nanotechnology, 24(1).
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  PMID: 23220884;Abstract: CdTe semiconductor nanocrystals (NCs) with 3-mercaptopropionic acid as the ligand exhibit a reversible response towards inter-switching oxygen and argon environments. The photoluminescence response is investigated at multiple oxygen concentrations, NC coverage and excitation intensities, in which all conditions exhibit full recovery upon exposure to flowing argon. The CdTe NC's large surface-to-volume ratio results in high sensitivity towards oxygen molecules with significant photoluminescence quenching at a concentration of 40 ppm. This suggests a novel approach to the creation of simple, inexpensive and ultrasensitive oxygen nanosensors. © 2013 IOP Publishing Ltd.
• Lau, P. C., Zhu, Z., Norwood, R. A., Mansuripur, M., & Peyghambarian, N. (2013). Thermally robust and blinking suppressed core/graded-shell CdSe/CdSe _1-xS_x/CdS 'giant' multishell semiconductor nanocrystals. Nanotechnology, 24(47).
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  PMID: 24177005;Abstract: We demonstrate that core/graded-shell CdSe/CdSe1-xS x/CdS giant semiconductor nanocrystals (g-NCs) have robust photoluminescence (PL) temperature response. At a size of 10.2 nm in diameter, these g-NCs undergo a PL drop of only 30% at 355 K relative to their PL intensity at 85 K. In comparison, the core/step-shell CdSe/CdS g-NCs at the same diameter exhibit 80% PL drop at 355 K. Spectral shifting and broadening were found to be, respectively, 5-10 times and 2-4 times smaller than those observed in standard CdSe core and CdSe/CdS core/shell NCs. These core/graded-shell g-NCs are largely blinking suppressed and have insignificant photoluminescence decay even after excitation at very high irradiance (44 kW cm-2) for over an hour. These types of g-NC have potential applications as the active medium for thermally robust laser devices (in the visible range) or as temperature-insensitive bioprobes for biomedical imaging. © 2013 IOP Publishing Ltd.
• Mansuripur, M. (2013). Mansuripur replies:. Physical Review Letters, 110(8).
• Mansuripur, M. (2013). Momentum exchange effect. Nature Photonics, 7(10), 765-766.
• Mansuripur, M. (2013). On the foundational equations of the classical theory of electrodynamics. Resonance, 18(2), 130-155.
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  Abstract: A close examination of the Maxwell-Lorentz theory of electrodynamics reveals that polarization and magnetization of material media need not be treated as local averages over small volumes - volumes that nevertheless contain a large number of electric and/or magnetic dipoles. Indeed, Maxwell's macroscopic equations are exact and self-consistent mathematical relations between electromagnetic fields and their sources, which consist of free charge, free current, polarization, and magnetization. When necessary, the discrete nature of the constituents of matter and the granularity of material media can be handled with the aid of special functions, such as Dirac's delta-function. The energy of the electromagnetic field and the exchange of this energy with material media are treated with a single postulate that establishes the Poynting vector S = E × H as the rate of flow of electromagnetic energy under all circumstances. Similarly, the linear and angular momentum densities of the fields are simple functions of the Poynting vector that can be unambiguously evaluated at all points in space and time, irrespective of the type of material media, if any, that might reside at various locations. Finally, we examine the Einstein-Laub force- and torque-density equations, and point out the consistency of these equations with the preceding postulates, with the conservation laws, and with the special theory of relativity. The set of postulates thus obtained constitutes a foundation for the classical theory of electrodynamics. © 2013 Indian Academy of Sciences.
• Mansuripur, M. (2013). The force law of classical electrodynamics: Lorentz versus einstein and laub. Proceedings of SPIE - The International Society for Optical Engineering, 8810.
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  Abstract: The classical theory of electrodynamics is built upon Maxwell's equations and the concepts of electromagnetic field, force, energy, and momentum, which are intimately tied together by Poynting's theorem and the Lorentz force law. Whereas Maxwell's macroscopic equations relate the electric and magnetic fields to their material sources (i.e., charge, current, polarization and magnetization), Poynting's theorem governs the flow of electromagnetic energy and its exchange between fields and material media, while the Lorentz law regulates the backand- forth transfer of momentum between the media and the fields. As it turns out, an alternative force law, first proposed in 1908 by Einstein and Laub, exists that is consistent with Maxwell's macroscopic equations and complies with the conservation laws as well as with the requirements of special relativity. While the Lorentz law requires the introduction of hidden energy and hidden momentum in situations where an electric field acts on a magnetic material, the Einstein-Laub formulation of electromagnetic force and torque does not invoke hidden entities under such circumstances. Moreover, the total force and the total torque exerted by electromagnetic fields on any given object turn out to be independent of whether force and torque densities are evaluated using the Lorentz law or in accordance with the Einstein-Laub formulas. Hidden entities aside, the two formulations differ only in their predicted force and torque distributions throughout material media. Such differences in distribution are occasionally measurable, and could serve as a guide in deciding which formulation, if either, corresponds to physical reality. © 2013 SPIE.
• Chang, C. M., Liu, Y. J., Tseng, M. L., Chu, N., Huang, D., Mansuripur, M., & Tsai, D. P. (2012). Characterization of Ge ₂Sb ₂Te ₅ thin film alloys using conductive-tip atomic force microscopy. Physica Status Solidi (B) Basic Research, 249(10), 1945-1950.
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  Abstract: Conductive-tip atomic force microscopy (C-AFM) is a powerful tool for investigating the electrical characteristics of phase-change materials commonly used for electronic and optical data storage. We demonstrate the usefulness of this technique by examining the electrical conductivity of crystalline marks recorded with a focused laser pulse on a thin Ge 2Sb 2Te 5 film. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
• Mansuripur, M. (2012). Angular momentum exchange between light and material media deduced from the Doppler shift. Proceedings of SPIE - The International Society for Optical Engineering, 8458.
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  Abstract: Electromagnetic waves carry energy as well as linear and angular momenta. When a light pulse is reflected from, transmitted through, or absorbed by a material medium, energy and momentum (both linear and angular) are generally exchanged, while the total amount of each entity remains intact. The extent of such exchanges between light and matter can be deduced, among other methods, with the aid of the Doppler shift phenomenon. The main focus of the present paper is on the transfer of angular momentum from a monochromatic light pulse to spinning objects such as a mirror, an absorptive dielectric, or a birefringent plate. The fact that individual photons of frequency ωo carry energy in the amount of ℏωo, where ℏ is Planck's reduced constant, enables one to relate the Doppler shift to the amount of energy exchanged. Under certain circumstances, the knowledge of exchanged energy leads directly to a determination of the momentum transferred from the photon to the material body, or vice versa. © 2012 SPIE.
• Mansuripur, M. (2012). Deducing radiation pressure on a submerged mirror from the Doppler shift. Physical Review A - Atomic, Molecular, and Optical Physics, 85(2).
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  Abstract: Radiation pressure on a flat mirror submerged in a transparent liquid depends not only on the refractive index n of the liquid but also on the phase angle ψ 0 of the Fresnel reflection coefficient of the mirror, which could be anywhere between 0 and 180. Depending on the value of ψ 0, the momentum per incident photon picked up by the mirror covers the range between the Abraham and Minkowski values, i.e., the interval (2ω 0/nc, 2nω 0/c). Here is the reduced Planck constant, ω 0 is the frequency of the incident photon, and c is the speed of light in vacuum. We argue that a simple experimental setup involving a dielectric slab of refractive index n, a vibrating mirror placed a short distance behind the slab, a collimated, monochromatic light beam illuminating the mirror through the slab, and an interferometer to measure the phase of the reflected beam is all that is needed to deduce the precise magnitude of the radiation pressure on a submerged mirror. In the proposed experiment, the transparent slab plays the role of the submerging liquid (even though it remains detached from the mirror at all times), and the adjustable gap between the mirror and the slab simulates the variable phase angle ψ 0. The phase of the reflected beam, measured as a function of time during one oscillation period of the mirror, then provides the information needed to determine the gap dependence of the reflected beam's Doppler shift and, consequently, the radiation pressure experienced by the mirror. © 2012 American Physical Society.
• Mansuripur, M. (2012). New perspective on the optical theorem of classical electrodynamics. American Journal of Physics, 80(4), 329-333.
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  Abstract: A proof of the optical theorem (also known as the optical cross-section theorem) is presented, which reveals the intimate connection between the forward scattering amplitude and the absorption-plus-scattering of the incident wave within the scatterer. The oscillating charges and currents as well as the electric and magnetic dipoles of the scatterer, driven by an incident plane wave, extract energy from the incident beam. The same oscillators radiate electromagnetic energy into the far field, thus giving rise to well-defined scattering amplitudes along various directions. The essence of the proof presented here is that the extinction cross-section of an object can be related to its forward scattering amplitude using the induced oscillations within the object without knowledge of the form assumed by these oscillations. © 2012 American Association of Physics Teachers.
• Mansuripur, M. (2012). Trouble with the Lorentz Law of force: Response to critics. Proceedings of SPIE - The International Society for Optical Engineering, 8455.
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  Abstract: In a recent paper, we questioned the validity of the Lorentz law of force in the presence of material media that contain electric and/or magnetic dipoles. A number of authors have criticized our methods and conclusions. This paper is an attempt at answering the critics and elaborating the relevant issues in some detail. © 2012 SPIE.
• Mansuripur, M. (2012). Trouble with the lorentz law of force: Incompatibility with special relativity and momentum conservation. Physical Review Letters, 108(19).
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  Abstract: The Lorentz law of force is the fifth pillar of classical electrodynamics, the other four being Maxwell's macroscopic equations. The Lorentz law is the universal expression of the force exerted by electromagnetic fields on a volume containing a distribution of electrical charges and currents. If electric and magnetic dipoles also happen to be present in a material medium, they are traditionally treated by expressing the corresponding polarization and magnetization distributions in terms of bound-charge and bound-current densities, which are subsequently added to free-charge and free-current densities, respectively. In this way, Maxwell's macroscopic equations are reduced to his microscopic equations, and the Lorentz law is expected to provide a precise expression of the electromagnetic force density on material bodies at all points in space and time. This Letter presents incontrovertible theoretical evidence of the incompatibility of the Lorentz law with the fundamental tenets of special relativity. We argue that the Lorentz law must be abandoned in favor of a more general expression of the electromagnetic force density, such as the one discovered by Einstein and Laub in 1908. Not only is the Einstein-Laub formula consistent with special relativity, it also solves the long-standing problem of "hidden momentum" in classical electrodynamics. © 2012 American Physical Society.
• Mansuripur, M., & Mansuripur, M. -. (2012). Trouble with the Lorentz law of force: incompatibility with special relativity and momentum conservation. Physical review letters, 108(19).
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  The Lorentz law of force is the fifth pillar of classical electrodynamics, the other four being Maxwell's macroscopic equations. The Lorentz law is the universal expression of the force exerted by electromagnetic fields on a volume containing a distribution of electrical charges and currents. If electric and magnetic dipoles also happen to be present in a material medium, they are traditionally treated by expressing the corresponding polarization and magnetization distributions in terms of bound-charge and bound-current densities, which are subsequently added to free-charge and free-current densities, respectively. In this way, Maxwell's macroscopic equations are reduced to his microscopic equations, and the Lorentz law is expected to provide a precise expression of the electromagnetic force density on material bodies at all points in space and time. This Letter presents incontrovertible theoretical evidence of the incompatibility of the Lorentz law with the fundamental tenets of special relativity. We argue that the Lorentz law must be abandoned in favor of a more general expression of the electromagnetic force density, such as the one discovered by Einstein and Laub in 1908. Not only is the Einstein-Laub formula consistent with special relativity, it also solves the long-standing problem of "hidden momentum" in classical electrodynamics.
• Mansuripur, M., & Zakharian, A. R. (2012). Radiation pressure and photon momentum in negative-index media. Proceedings of SPIE - The International Society for Optical Engineering, 8455.
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  Abstract: Radiation pressure and photon momentum in negative-index media are no different than their counterparts in ordinary (positive-index) materials. This is because the parameters responsible for these properties are the admittance √ε/μ and the group refractive index ng of the material (both positive entities), and not the phase refractive index n = √εμ, which is negative in negative-index media. One approach to investigating the exchange of momentum between electromagnetic waves and material media is via the Doppler shift phenomenon. In this paper we use the Doppler shift to arrive at an expression for the radiation pressure on a mirror submerged in a negative-index medium. In preparation for the analysis, we investigate the phenomenon of Doppler shift in various settings, and show the conditions under which a so-called "inverse" Doppler shift could occur. We also argue that a recent observation of the inverse Doppler shift upon reflection from a negative-index medium cannot be correct, because it violates the conservation laws. © 2012 SPIE.
• Mansuripur, M., & Zakharian, A. R. (2012). Radiation pressure on a submerged absorptive partial reflector deduced from the Doppler shift. Physical Review A - Atomic, Molecular, and Optical Physics, 86(1).
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  Abstract: When a light pulse is reflected from a mirror, energy and momentum are exchanged between the electromagnetic field and the material medium. The resulting change in the energy of the reflected photons is directly related to their Doppler shifts arising from the change in the state of motion of the mirror. Similarly, the Doppler shift of photons that enter an absorber is intimately tied to the kinetic energy and momentum acquired by the absorber in its interaction with the incident light. The argument from the Doppler shift yields expressions for the exchanged energy and momentum that are identical with those obtained from Maxwell's equations and the Lorentz law of force, despite the fact that the physical bases of the two methods are fundamentally different. Here, we apply the Doppler-shift argument to a submerged partial reflector (one that absorbs a fraction of the incident light), deducing, in the process, the magnitude of the photon momentum within the submerging medium. We also discuss the case of the submerging medium having a negative refractive index and show the absence of the so-called "reversed" Doppler shift when the reflector is detached from the negative-index medium. © 2012 American Physical Society.
• Chang, C. M., Chu, C. H., Tseng, M. L., Chiang, H., Mansuripur, M., & Tsai, D. P. (2011). Local electrical characterization of laser-recorded phase-change marks on amorphous Ge₂Sb₂Te₅ thin films. Optics Express, 19(10), 9492-9504.
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  PMID: 21643206;Abstract: Amorphous thin films of Ge2Sb2Te5, sputter-deposited on a thin-film gold electrode, are investigated for the purpose of understanding the local electrical conductivity of recorded marks under the influence of focused laser beam. Being amorphous, the as-deposited chalcogenide films have negligible electrical conductivity. With the aid of a focused laser beam, however, we have written on these films micron-sized crystalline marks, ablated holes surrounded by crystalline rings, and other multi-ring structures containing both amorphous and crystalline zones. Within these structures, nano-scale regions of superior local conductivity have been mapped and probed using our high-resolution, high-sensitivity conductive-tip atomic force microscope (C-AFM). Scanning electron microscopy and energy-dispersive spectrometry have also been used to clarify the origins of high conductivity in and around the recorded marks. When the Ge 2Sb2Te5 layer is sufficiently thin, and when laser crystallization/ablation is used to define long isolated crystalline stripes on the samples, we find the C-AFM-based method of extracting information from the recorded marks to be superior to other forms of microscopy for this particular class of materials. Given the tremendous potential of chalcogenides as the leading media candidates for high-density memories, local electrical characterization of marks recorded on as-deposited amorphous Ge 2Sb2Te5 films provides useful information for furthering research and development efforts in this important area of modern technology. © 2011 Optical Society of America.
• Chang, C. M., Tseng, M. L., Chu, C. H., Mansuripur, M., & Tsai, D. P. (2011). Physical and chemical characterization of laser-recorded phase-change marks on amorphous ge₂sb₂te₅ thin films. Optics InfoBase Conference Papers.
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  Abstract: As-deposited thin films of Ge2Sb2Te5 are investigated for the purpose of understanding the local electrical conductivity and structural phase-transitions of recorded marks under the influence of focused laser beam. We have written on these films micron-sized crystalline marks, ablated holes surrounded by crystalline rings, and other multi-ring structures containing both amorphous and crystalline zones with the aid of a focused laser beam. The high-contrast conductivity of GST recorded marks under various illumination conditions were investigated using Conductive-Atomic Force Microscopy (C-AFM). Also, selective chemical etching of recorded marks in conjunction with optical, atomic force, and electron microscopy as well as local electron diffraction analysis are used to discern the complex structural features created under a broad range of laser powers and pulse durations. Clarifying the nature of physical and chemical characterization associated with laser-recorded marks in chalcogenide Ge2Sb2Te5 thin films provides useful information for reversible optical and electronic data storage, as well as for phase-change (thermal) lithography. © 2011 OSA.
• Chen, W. T., Wu, P. C., Chen, C. J., Weng, C., Lee, H., Yen, T., Kuan, C., Mansuripur, M., & Tsai, D. P. (2011). Manipulation of multi-dimensional plasmonic spectra for information storage. Optics InfoBase Conference Papers.
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  Abstract: We demonstrate a concept of optical data storage through plasmonic resonances of metallic nano-structures. Metallic nano-structures exhibit strong variations in their reflectance and/or transmittance spectra due to surface plasmon polariton resonances. We study the variations of spectra through 50×50 arrays of repeated unit cells covering a total area of ~50×50 μm2. Each cell contains 10 different nano-features, such as an ellipse, a ring, a circle, a triangle, a square, etc. The size of each unit-cell is 500×500 nm2, and the periodicity is 1.0 μm. The variations of spectra are obvious enough to be distinguished and then retrieved. © 2011 Optical Society of America.
• Chen, W. T., Wu, P. C., Chen, C. J., Weng, C., Lee, H., Yen, T., Kuan, C., Mansuripur, M., & Tsai, D. P. (2011). Manipulation of multidimensional plasmonic spectra for information storage. Applied Physics Letters, 98(17).
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  Abstract: We demonstrate a concept of optical data storage through plasmonic resonances of metallic nanostructures. Metallic nanostructures exhibit strong variations in their reflectance and/or transmittance spectra due to surface plasmon polariton resonances. We study the variations in spectra through 50×50 arrays of repeated unit cells covering a total area of ∼50×50 μ m2. Each cell contains ten different nanofeatures, such as an ellipse, a ring, a circle, a triangle, a square, etc. The size of each unit-cell is 500×500 nm2, and the periodicity is 1.0 μm. The variations in spectra are obvious enough to be distinguished and then retrieved. © 2011 American Institute of Physics.
• Chu, C. H., Tseng, M. L., Shiue, C. D., Chen, S. W., Chiang, H., Mansuripur, M., & Tsai, D. P. (2011). Fabrication of phase-change Ge₂Sb₂Te₅ nano-rings. Optics Express, 19(13), 12652-12657.
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  PMID: 21716507;Abstract: Phase-change material Ge2Sb2Te5 rings with nanometer-scale thickness have been fabricated using the photo-thermal effect of a focused laser beam followed by differential chemical etching. Laser irradiation conditions and etching process parameters are varied to control the geometric characteristics of the rings. We demonstrate the possibility of arranging the rings in specific geometric patterns, and also their release from the original substrate. © 2011 Optical Society of America.
• Mansuripur, M. (2011). Field, force, energy and momentum in classical Electrodynamics. Field, Force, Energy and Momentum in Classical Electrodynamics.
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  Abstract: This book grew out of a graduate-level course in electrodynamics that I have taught at the University of Arizona's College of Optical Sciences over the past six years. A typical student enrolled in the course is a first year graduate student in Optical Sciences, Electrical Engineering, or Physics, who has had some prior exposure to electromagnetic theory. The level of mathematics required for this subject is not particularly advanced; students are expected to be familiar with calculus, vector algebra, complex numbers, ordinary differential equations, and elementary aspects of the Fourier transform theory. Most of the mathematical tools and techniques needed for developing the theory of electrodynamics are in fact interwoven with the course material in the form of a section here, a chapter there, or a few problems at the end of each chapter. The student is thus motivated to learn the required mathematics in the relevant physical context whenever the need arises. © 2011 Bentham Science Publishers Ltd. All rights reserved.
• Mansuripur, M. (2011). Nature of electric and magnetic dipoles gleaned from the Poynting theorem and the Lorentz force law of classical electrodynamics. Optics Communications, 284(2), 594-602.
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  Abstract: Starting with the most general form of Maxwell's macroscopic equations in which the free charge and free current densities, ρfree and Jfree, as well as the densities of polarization and magnetization, P and M, are arbitrary functions of space and time, we compare and contrast two versions of the Poynting vector, namely, S = μo- 1E × B and S = E × H. Here E is the electric field, H is the magnetic field, B is the magnetic induction, and μo is the permeability of free space. We argue that the identification of one or the other of these Poynting vectors with the rate of flow of electromagnetic energy is intimately tied to the nature of magnetic dipoles and the way in which these dipoles exchange energy with the electromagnetic field. In addition, the manifest nature of both electric and magnetic dipoles in their interactions with the electromagnetic field has consequences for the Lorentz law of force. If the conventional identification of magnetic dipoles with Amperian current loops is extended beyond Maxwell's macroscopic equations to the domain where energy, force, torque, momentum, and angular momentum are active participants, it will be shown that "hidden energy" and "hidden momentum" become inescapable consequences of such identification with Amperian current loops. Hidden energy and hidden momentum can be avoided, however, if we adopt S = E × H as the true Poynting vector, and also accept a generalized version of the Lorentz force law. We conclude that the identification of magnetic dipoles with Amperian current loops, while certainly acceptable within the confines of Maxwell's macroscopic equations, is inadequate and leads to complications when considering energy, force, torque, momentum, and angular momentum in electromagnetic systems that involve the interaction of fields and matter. © 2010 Elsevier B.V. All rights reserved.
• Mansuripur, M. (2011). Solar sails, optical tweezers, and other light-driven machines. Proceedings of SPIE - The International Society for Optical Engineering, 8122.
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  Abstract: Electromagnetic waves carry energy, linear momentum, and angular momentum. When light (or other electromagnetic radiation) interacts with material media, both energy and momentum are usually exchanged. The force and torque experienced by material bodies in their interactions with the electromagnetic field are such that the energy as well as the linear and angular momenta of the overall system (i.e., the system of field plus matter) are conserved. Radiation forces are now used routinely to trap and manipulate small objects such as glass or plastic micro-beads and biological cells, to drive micro- and nanomachines, and to contemplate interstellar travel with the aid of solar sails. We discuss the properties of the electromagnetic field that enable such wide-ranging applications. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
• Mansuripur, M. (2011). Spin and orbital angular momenta of electromagnetic waves in free space. Physical Review A - Atomic, Molecular, and Optical Physics, 84(3).
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  Abstract: We derive exact expressions, in the form of Fourier integrals over the (k,ω) domain, for the energy, momentum, and angular momentum of a light pulse propagating in free space. The angular momentum is seen to split naturally into two parts. The spin contribution of each plane-wave constituent of the pulse, representing the difference between its right- and left-circular polarization content, is aligned with the corresponding k-vector. In contrast, the orbital angular momentum associated with each plane-wave is orthogonal to its k-vector. In general, the orbital angular momentum content of the wavepacket is the sum of an intrinsic part, due, for example, to phase vorticity, and an extrinsic part, rCM × p, produced by the linear motion of the center-of-mass rCM of the light pulse in the direction of its linear momentum p. © 2011 American Physical Society.
• Mansuripur, M. (2011). The role of nano-technology in data storage devices and systems. Optics InfoBase Conference Papers.
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  Abstract: As data storage technologies evolve and new applications emerge, the balance among electronic, magnetic, and optical modes of storage shifts in ways that are not always predictable. Commercial success of a given technology, however, is invariably tied to its ability to continually shrink the spatial dimensions of individual bits. © 2011 OSA.
• Mansuripur, M., & Tsai, D. P. (2011). New perspective on the reciprocity theorem of classical electrodynamics. Optics Communications, 284(3), 707-714.
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  Abstract: We provide a simple physical proof of the reciprocity theorem of classical electrodynamics in the general case of material media that contain linearly polarizable as well as linearly magnetizable substances. The excitation source is taken to be a point-dipole, either electric or magnetic, and the monitored field at the observation point can be electric or magnetic, regardless of the nature of the source dipole. The electric and magnetic susceptibility tensors of the material system may vary from point to point in space, but they cannot be functions of time. In the case of spatially non-dispersive media, the only other constraint on the local susceptibility tensors is that they be symmetric at each and every point. The proof is readily extended to media that exhibit spatial dispersion: For reciprocity to hold, the electric susceptibility tensor χE-mn that relates the complex-valued magnitude of the electric dipole at location rm to the strength of the electric field at r n must be the transpose of χE-nm. Similarly, the necessary and sufficient condition for the magnetic susceptibility tensor is χM-mn = χTM-nm. © 2010 Elsevier B.V. All rights reserved.
• Tseng, M. L., Chen, B. H., Chu, C. H., Chang, C. M., Lin, W. C., Chu, N., Mansuripur, M., Liu, A. Q., & Tsai, D. P. (2011). Fabrication of phase-change chalcogenide Ge₂Sb ₂Te₅ patterns by laser-induced forward transfer. Optics Express, 19(18), 16975-16984.
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  PMID: 21935057;Abstract: Femtosecond laser pulses are focused on a thin film of Ge 2Sb2Te5 phase-change material, and the transfer of the illuminated material to a nearby substrate is investigated. The size, shape, and phase-state of the fabricated pattern can be effectively controlled by the laser fluence and by the thickness of the Ge2Sb2Te5 film. Results show multi-level electrical and optical reflection states of the fabricated patterns, which may provide a simple and efficient foundation for patterning future phase-change devices. © 2011 Optical Society of America.
• Tseng, M. L., Chu, C. H., Chang, C. M., Lin, W. C., Chu, N., Mansuripur, M., Liu, A. Q., & Tsai, D. P. (2011). Femto-second laser fabrication of phase change material nanostructures for novel applications. Optics InfoBase Conference Papers, 1182-1184.
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  Abstract: In this paper, we will demonstrate our recent results of laser lithography of nanostructures of phase change material for novel nanophotonic application. © 2011 AOS.
• Chu, C. H., Shiue, C. D., Cheng, H. W., Tseng, M. L., Chiang, H., Mansuripur, M., & Tsai, D. P. (2010). Laser-induced phase transitions of Ge₂Sb₂Te ₅ thin films used in optical and electronic data storage and in thermal lithography. Optics Express, 18(17), 18383-18393.
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  PMID: 20721232;Abstract: Amorphous thin films of Ge2Sb2Te5, sputter-deposited on a ZnS-SiO2 dielectric layer, are investigated for the purpose of understanding the structural phase-transitions that occur under the influence of tightly-focused laser beams. Selective chemical etching of recorded marks in conjunction with optical, atomic force, and electron microscopy as well as local electron diffraction analysis are used to discern the complex structural features created under a broad range of laser powers and pulse durations. Clarifying the nature of phase transitions associated with laser-recorded marks in chalcogenide Ge2Sb2Te5 thin films provides useful information for reversible optical and electronic data storage, as well as for phase-change (thermal) lithography. © 2010 Optical Society of America.
• Mansuripur, M. (2010). Resolution of the Abraham-Minkowski controversy. Optics Communications, 283(10), 1997-2005.
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  Abstract: The momentum of light inside ponderable media has an electromagnetic part and a mechanical part. The local and instantaneous density of the electromagnetic part of the momentum is given by the Poynting vector divided by the square of the speed of light in vacuum, irrespective of the nature of the electromagnetic fields or the local or global properties of the material media. The mechanical part of the momentum is associated with the action of the electromagnetic field on the atomic constituents of the media, as specified by the Lorentz law of force. Proper interpretation and application of the Maxwell-Lorentz equations within the material bodies as well as at their surfaces and interfaces is all that is needed to obtain a complete picture of the momentum of light, including detailed numerical values at each and every point in space and time. That the Abraham-Minkowski controversy surrounding the momentum of light inside material media has persisted for nearly a century is due perhaps to an insufficient appreciation for the completeness and consistency of the macroscopic Maxwell-Lorentz theory, inadequate treatment of the electromagnetic force and torque at the material boundaries, and an undue emphasis on the necessity of coupling the equations of electrodynamics to those of the theory of elasticity for proper treatment of mechanical momentum. The present paper reports the resolution of the Abraham-Minkowski controversy within the framework of the classical theory of electrodynamics, without resort to such complicating and ultimately unnecessary factors as pseudo-momentum, special surface forces, alternative energy-momentum tensors, and hidden momenta, that have caused so much confusion for such a long period of time. © 2010 Elsevier B.V. All rights reserved.
• Mansuripur, M., & Zakharian, A. R. (2010). Energy, momentum, and force in classical electrodynamics: Application to negative-index media. Optics Communications, 283(23), 4594-4600.
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  Abstract: The classical theory of electromagnetism is based on Maxwell's macroscopic equations, an energy postulate, a momentum postulate, and a generalized form of the Lorentz law of force. These seven postulates constitute the foundation of a complete and consistent theory, thus eliminating the need for physical models of polarization P and magnetization M - these being the distinguishing features of Maxwell's macroscopic equations. In the proposed formulation, P(r, t) and M(r, t) are arbitrary functions of space and time, their physical properties being embedded in the seven postulates of the theory. The postulates are self-consistent, comply with special relativity, and satisfy the laws of conservation of energy, linear momentum, and angular momentum. The Abraham momentum density pEM(r,t) = E(r,t) × H(r,t) / c2 emerges as the universal electromagnetic momentum that does not depend on whether the field is propagating or evanescent, and whether or not the host media are homogeneous, transparent, isotropic, linear, dispersive, magnetic, hysteretic, negative-index, etc. Any variation with time of the total electromagnetic momentum of a closed system results in a force exerted on the material media within the system in accordance with the generalized Lorentz law. © 2010 Elsevier B.V. All rights reserved.
• Mansuripur, M., & Zakharian, A. R. (2010). Whence the Minkowski momentum?. Optics Communications, 283(19), 3557-3563.
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  Abstract: Electromagnetic waves carry the Abraham momentum, whose density is given by pEM = S(r,t) / c2. Here S(r,t) = E(r,t) × H(r,t) is the Poynting vector at point r in space and instant t in time, E and H are the local electromagnetic fields, and c is the speed of light in vacuum. The above statement is true irrespective of whether the waves reside in vacuum or within a ponderable medium, which medium may or may not be homogeneous, isotropic, transparent, linear, magnetic, etc. When a light pulse enters an absorbing medium, the force experienced by the medium is only partly due to the absorbed Abraham momentum. This absorbed momentum, of course, is manifested as Lorentz force (while the pulse is being extinguished within the absorber), but not all the Lorentz force experienced by the medium is attributable to the absorbed Abraham momentum. We consider an absorptive/reflective medium having the complex refractive index n2 + iκ2, submerged in a transparent dielectric of refractive index n1, through which light must travel to reach the absorber/reflector. Depending on the impedance-mismatch between the two media, which mismatch is dependent on n1, n 2, κ2, either more or less light will be coupled into the absorber/reflector. The dependence of this impedance-mismatch on n 1 is entirely responsible for the appearance of the Minkowski momentum in certain radiation pressure experiments that involve submerged objects. © 2010 Elsevier B.V. All rights reserved.
• Deng, Z., Chen, D., Tang, F., & Mansuripur, M. (2009). Growth of single-crystal double-directional tellurium nanoneedles from CdTe nnocrystals in slution. Crystal Growth and Design, 9(4), 1823-1828.
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  Abstract: Single-crystal double-directional tellurium (Te) nanoneedles were grown by a facile route of air oxidation of CdTe nanocrystals in aqueous solution containing ammonia. The as-synthesized Te nanoneedles with a relatively high yield and uniformity grew along the [001] crystalline direction with lengths of 2-4 μm and stem diameters of 80-120 nm, and gradually becoming thinner to form sharp tips of sub-5 nm. The double-directional nanoneedles were straight, with high purity, well-crystallized, and dislocation-free, according to range of methods such as X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission microscopy, and selected area electron diffraction. The detailed transformation process from CdTe nanocrystals to single-crystal double-directional Te nanoneedles was studied. It is expected that the single-crystal double-directional Te nanoneedles would be a very promising new member of field emitters, probes of atomic force microscopy, and used in the manufacture of functional nanodevices. © 2009 American Chemical Society.
• Mansuripur, M. (2009). Can future storage technologies benefit from existing or emerging nano-tools and techniques. Proceedings of SPIE - The International Society for Optical Engineering, 7505.
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  Abstract: Certain ideas and techniques are being developed outside the field of optical/magnetic/ electronic recording, but the storage community could benefit from these developments once we become sufficiently familiar with the new concepts and methodologies. Developments in the areas of nano- and bio-photonics, fluorescence microscopy, quantum-dots, optical tweezers, micro- and nano-fluidics, femtosecond lasers, etc., have the potential to influence future generations of data storage systems. © 2009 SPIE.
• Mansuripur, M. (2009). Comment on "observation of a push force on the end face of a nanometer silica filament exerted by outgoing light". Physical Review Letters, 103(1).
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  Abstract: A Comment on the Letter by Weilong She, Jianhui Yu, and Raohui Feng, Phys. Rev. Lett.PRLTAO0031-9007 101, 243601 (2008)10.1103/PhysRevLett.101.243601. © 2009 The American Physical Society.
• Mansuripur, M., & Zakharian, A. R. (2009). Energy, momentum, and force in classical electrodynamics: Application to negative-index media. Proceedings of SPIE - The International Society for Optical Engineering, 7392.
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  Abstract: The classical theory of electromagnetism is based on Maxwell's macroscopic equations, an energy postulate, a momentum postulate, and a generalized form of the Lorentz law of force. These seven postulates constitute the foundation of a complete and consistent theory, thus eliminating the need for physical models of polarization P and magnetization M - these being the distinguishing features of Maxwell's macroscopic equations. In the proposed formulation, P(r,t) and M(r,t) are arbitrary functions of space and time, their physical properties being embedded in the seven postulates of the theory. The postulates are self-consistent, comply with special relativity, and satisfy the laws of conservation of energy, linear momentum, and angular momentum. The Abraham momentum density pEM(r,t)=E(r, t)×H(r,t)/c2 emerges as the universal electromagnetic momentum that does not depend on whether the field is propagating or evanescent, and whether or not the host media are homogeneous, transparent, isotropic, linear, dispersive, magnetic, hysteretic, negative-index, etc. Any variation with time of the total electromagnetic momentum of a closed system results in a force exerted on the material media within the system in accordance with the generalized Lorentz law. © 2009 SPIE.
• Mansuripur, M., & Zakharian, A. R. (2009). Maxwell's macroscopic equations, the energy-momentum postulates, and the Lorentz law of force. Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 79(2).
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  Abstract: We argue that the classical theory of electromagnetism is based on Maxwell's macroscopic equations, an energy postulate, a momentum postulate, and a generalized form of the Lorentz law of force. These seven postulates constitute the foundation of a complete and consistent theory, thus eliminating the need for actual (i.e., physical) models of polarization P and magnetization M, these being the distinguishing features of Maxwell's macroscopic equations. In the proposed formulation, P (r,t) and M (r,t) are arbitrary functions of space and time, their physical properties being embedded in the seven postulates of the theory. The postulates are self-consistent, comply with the requirements of the special theory of relativity, and satisfy the laws of conservation of energy, linear momentum, and angular momentum. One advantage of the proposed formulation is that it sidesteps the long-standing Abraham-Minkowski controversy surrounding the electromagnetic momentum inside a material medium by simply "assigning" the Abraham momentum density E (r,t) ×H (r,t) c2 to the electromagnetic field. This well-defined momentum is thus taken to be universal as it does not depend on whether the field is propagating or evanescent, and whether or not the host medium is homogeneous, transparent, isotropic, dispersive, magnetic, linear, etc. In other words, the local and instantaneous momentum density is uniquely and unambiguously specified at each and every point of the material system in terms of the E and H fields residing at that point. Any variation with time of the total electromagnetic momentum of a closed system results in a force exerted on the material media within the system in accordance with the generalized Lorentz law. © 2009 The American Physical Society.
• Mansuripur, M., & Zakharian, A. R. (2009). Theoretical analysis of the force on the end face of a nanofilament exerted by an outgoing light pulse. Physical Review A - Atomic, Molecular, and Optical Physics, 80(2).
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  Abstract: The slight deformations observed upon transmission of a light pulse through a short length of a silica glass nanofilament offer the possibility of determining the momentum of light inside the filament. Using precise numerical calculations that take into account not only the electromagnetic momentum inside and outside the filament, but also the Lorentz force exerted by a light pulse in its entire path through the nanowaveguide, we conclude that the net effect of a short pulse exiting the nanofilament should be a pull force on the end face of the filament. © 2009 The American Physical Society.
• Mansuripur, M., & Zakharian, A. R. (2009). What is wrong with the interpretation of recent nano-filament experiments?. Proceedings of SPIE - The International Society for Optical Engineering, 7400.
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  Abstract: In a recent paper, W. She, J. Yu and R. Feng reported the slight deformations observed upon transmission of a light pulse through a short length of a silica glass nano-filament. Relating the shape and magnitude of these deformations to the momentum of the light pulse inside and outside the filament, these authors concluded that, within the fiber, the photons carry the Abraham momentum. We present an alternative evaluation of force and momentum in a system similar to the experimental setup of She et al. Using precise numerical calculations that take into account not only the electromagnetic momentum inside and outside the filament, but also the Lorentz force exerted by a light pulse in its entire path through the nano-waveguide, we conclude that the net effect should be a pull (rather than a push) force on the end face of the nano-filament. © 2009 SPIE.
• Mansuripur, M., & Zakharian, A. R. (2009). Whence the minkowski momentum?. Proceedings of SPIE - The International Society for Optical Engineering, 7400.
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  Abstract: Electromagnetic waves carry the Abraham momentum, whose density is given by pEM = S(r, t)/c2. Here S(r, t) = E(r, t)×H(r, t) is the Poynting vector at point r in space and instant t in time, E and H are the local electromagnetic fields, and c is the speed of light in vacuum. The above statement is true irrespective of whether the waves reside in vacuum or within a ponderable medium, which medium may or may not be homogeneous, isotropic, transparent, linear, magnetic, etc. When a light pulse enters an absorbing medium, the force experienced by the medium is only partly due to the absorbed Abraham momentum. This absorbed momentum, of course, is manifested as Lorentz force (while the pulse is being extinguished within the absorber), but not all the Lorentz force experienced by the medium is attributable to the absorbed Abraham momentum. We consider an absorptive/reflective medium having the complex refractive index n2+ik2, submerged in a transparent dielectric of refractive index n1, through which light must travel to reach the absorber/reflector. Depending on the impedance-mismatch between the two media, which mismatch is dependent on n1, n2, k 2, either more or less light will be coupled into the absorber/reflector. The dependence of this impedance-mismatch on n1 is entirely responsible for the appearance of the Minkowski momentum in certain radiation pressure experiments that involve submerged objects. © 2009 SPIE.
• Yoda, H., Polynkin, P., & Mansuripur, M. (2009). Erratum: "Beam quality factor of higher order modes in a step-index fiber" (Journal of Lightwave Technology). Journal of Lightwave Technology, 27(9), 1237-.
• Mansuripur, M. (2008). Electromagnetic force and torque in ponderable media. Optics Express, 16(19), 14821-14835.
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  PMID: 18795019;Abstract: Maxwell's macroscopic equations combined with a generalized form of the Lorentz law of force are a complete and consistent set of equations. Not only are these five equations fully compatible with special relativity, they also conform with conservation laws of energy, momentum, and angular momentum. We demonstrate consistency with the conservation laws by showing that, when a beam of light enters a magnetic dielectric, a fraction of the incident linear (or angular) momentum pours into the medium at a rate determined by the Abraham momentum density, E×H/c2, and the group velocity Vg of the electromagnetic field. The balance of the incident, reflected, and transmitted momenta is subsequently transferred to the medium as force (or torque) at the leading edge of the beam, which propagates through the medium with velocity Vg. Our analysis does not require "hidden" momenta to comply with the conservation laws, nor does it dissolve into ambiguities with regard to the nature of electromagnetic momentum in ponderable media. The linear and angular momenta of the electromagnetic field are clearly associated with the Abraham momentum, and the phase and group refractive indices (np and ng) play distinct yet definitive roles in the expressions of force, torque, and momentum densities. © 2008 Optical Society of America.
• Mansuripur, M. (2008). Generalized Lorentz Law and the force of radiation on magnetic dielectrics. Proceedings of SPIE - The International Society for Optical Engineering, 7038.
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  Abstract: The macroscopic equations of Maxwell combined with a generalized form of the Lorentz law are a complete and consistent set; not only are these five equations fully compatible with the special theory of relativity, they also conform with the conservation laws of energy, momentum, and angular momentum. The linear momentum density associated with the electromagnetic field is p EM(r,t)=E(r,t)×H(r,t)/c2, whether the field is in vacuum or in a ponderable medium. [Homogeneous, linear, isotropic media are typically specified by their electric and magnetic permeabilities εo ε(ω) and μoμ(ω).] The electromagnetic momentum residing in a ponderable medium is often referred to as Abraham momentum. When an electromagnetic wave enters a medium, say, from the free space, it brings in Abraham momentum at a rate determined by the density distribution pEM(r,t), which spreads within the medium with the light's group velocity. The balance of the incident, reflected, and transmitted (electromagnetic) momenta is subsequently transferred to the medium as mechanical force in accordance with Newton's second law. The mechanical force of the radiation field on the medium may also be calculated by a straightforward application of the generalized form of the Lorentz law. The fact that these two methods of force calculation yield identical results is the basis of our claim that the equations of electrodynamics (Maxwell + Lorentz) comply with the momentum conservation law. When applying the Lorentz law, one must take care to properly account for the effects of material dispersion and absorption, discontinuities at material boundaries, and finite beam dimensions. This paper demonstrates some of the issues involved in such calculations of the electromagnetic force in magnetic dielectric media.
• Mansuripur, M., & Mansuripur, M. -. (2008). Electromagnetic force and torque in ponderable media. Optics express, 16(19).
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  Maxwell's macroscopic equations combined with a generalized form of the Lorentz law of force are a complete and consistent set of equations. Not only are these five equations fully compatible with special relativity, they also conform with conservation laws of energy, momentum, and angular momentum. We demonstrate consistency with the conservation laws by showing that, when a beam of light enters a magnetic dielectric, a fraction of the incident linear (or angular) momentum pours into the medium at a rate determined by the Abraham momentum density, E x H/c(2), and the group velocity V(g) of the electromagnetic field. The balance of the incident, reflected, and transmitted momenta is subsequently transferred to the medium as force (or torque) at the leading edge of the beam, which propagates through the medium with velocity V(g). Our analysis does not require "hidden" momenta to comply with the conservation laws, nor does it dissolve into ambiguities with regard to the nature of electromagnetic momentum in ponderable media. The linear and angular momenta of the electromagnetic field are clearly associated with the Abraham momentum, and the phase and group refractive indices (n(p) and n(g)) play distinct yet definitive roles in the expressions of force, torque, and momentum densities.
• Mansuripur, M., & Mansuripur, M. -. (2008). Electromagnetic stress tensor in ponderable media. Optics express, 16(8).
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  We derive an expression for the Maxwell stress tensor in a magnetic dielectric medium specified by its permittivity epsilon and permeability micro. The derivation proceeds from the generalized form of the Lorentz law, which specifies the force exerted by the electromagnetic E and H fields on the polarization P and magnetization M of a ponderable medium. Our stress tensor differs from the well-known tensors of Abraham and Minkowski, which have been at the center of a century-old controversy surrounding the momentum of the electromagnetic field in transparent materials.
• Mansuripur, M., Kieu, K., & Mansuripur, M. -. (2008). All-fiber bidirectional passively mode-locked ring laser. Optics letters, 33(1).
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  We report the design and operation of a novel all-fiber bidirectional passively mode-locked ring laser. An erbium-doped fiber was chosen as the active element in a ring cavity arrangement. A short segment of a fiber taper embedded in carbon nanotubes/polymer composite, acting as a saturable absorber, was used to enable bidirectional mode locking. The laser generates two stable femtosecond pulse trains in opposite directions. A beat note of about 2 MHz, having a bandwidth of less than 2 kHz, is measured when the pulses propagating in opposite directions are (temporally) overlapped at a photodetector. We believe this device will find important applications in precision rotation sensing.
• Kalkum, F., Gay, G., Alloschery, O., Weiner, J., Lezec, H. J., Xie, Y., & Mansuripur, M. (2007). Surface-wave interferometry on single subwavelength slit-groove structures fabricated on gold films. Optics Express, 15(5), 2613-2621.
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  PMID: 19532500;Abstract: We apply the technique of far-field interferometry to measure the properties of surface waves generated by two-dimensional (2D) single subwavelength slit-groove structures on gold films. The effective surface index of refraction nsurf measured for the surface wave propagating over a distance of more than 12 μm is determined to be nsurf = 1.016 ±0.004, to within experimental uncertainty close to the expected bound surface plasmon-polariton (SPP) value for a Au/Air interface of nSpp = 1.018. We compare these measurements to finite-difference-time-domain (FDTD) numerical simulations of the optical field transmission through these devices. We find excellent agreement between the measurements and the simulations for nsurf. The measurements also show that the surface wave propagation parameter ksurf exhibits transient behavior close to the slit, evolving smoothly from greater values asymptotically toward kspp over the first 2-3 μm of slit-groove distance xsg. This behavior is confirmed by the FDTD simulations. © 2007 Optical Society of America.
• Mansuripur, M. (2007). Modeling diffractive optical elements for optical data storage applications. Proceedings of SPIE - The International Society for Optical Engineering, 6620.
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  Abstract: A combination of ray-tracing and diffraction theory is used to model the diffractive optical elements used in optical data storage systems. Details of the theoretical model and some numerical simulation results are presented.
• Mansuripur, M. (2007). Momentum of the electromagnetic field in transparent dielectric media. Proceedings of SPIE - The International Society for Optical Engineering, 6644.
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  Abstract: We present arguments in favor of the proposition that the momentum of light inside a transparent dielectric medium is the arithmetic average of the Minkowski and Abraham momenta. Using the Lorentz transformation of the fields (and of the coordinates) from a stationary to a moving reference frame, we show the consistent transformation of electromagnetic energy and momentum between the two frames. We also examine the momentum of static (i.e., timeindependent) electromagnetic fields, and show that the close connection that exists between the Poynting vector and the momentum density extends all the way across the frequency spectrum to this zero-frequency limit. In the specific example presented in this paper, the static field inside a non-absorbing dielectric material turns out to have the Minkowski momentum.
• Mansuripur, M. (2007). Radiation pressure and the linear momentum of the electromagnetic field in magnetic media. Optics Express, 15(21), 13502-13517.
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  PMID: 19550619;Abstract: We examine the force of the electromagnetic radiation on linear, isotropic, homogeneous media specified in terms of their permittivity e and permeability μ. A formula is proposed for the electromagnetic Lorentz force on the magnetization M, which is treated here as an Amperian current loop. Using the proposed formula, we demonstrate conservation of momentum in several cases that are amenable to rigorous analysis based on the classical Maxwell equations, the Lorentz law of force, and the constitutive relations. Our analysis yields precise expressions for the density of the electromagnetic and mechanical momenta inside the media that are specified by their (ε,μ) parameters. An interesting consequence of this analysis is the identification of an "intrinsic" mechanical momentum density, 1/2E ×M/c2, analogous to the electromagnetic (or Abraham) momentum density, 1/2E ×H/c2. (Here E and H are the magnitudes of the electric and magnetic fields, respectively, and c is the speed of light in vacuum.) This intrinsic mechanical momentum, associated with the magnetization M in the presence of an electric field E, is apparently the same "hidden" momentum that was predicted by W. Shockley and R. P. James nearly four decades ago. © 2007 Optical Society of America.
• Mansuripur, M. (2007). Radiation pressure on submerged mirrors: Implications for the momentum of light in dielectric media. Optics Express, 15(5), 2677-2682.
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  PMID: 19532504;Abstract: Radiation pressure measurements on mirrors submerged in dielectric liquids have consistently shown an effective Minkowski momentum for the photons within the liquid. Using an exact theoretical calculation based on Maxwell's equations and the Lorentz law of force, we demonstrate that this result is a consequence of the fact that conventional mirrors impart, upon reflection, a 180° phase shift to the incident beam of light. If the mirror is designed to impart a different phase, then the effective momentum will turn out to be anywhere between the two extremes of the Minkowski and Abraham momenta. Since all values in the range between these two extremes are equally likely to be found in experiments, we argue that the photon momentum inside a dielectric host has the arithmetic mean value of the Abraham and Minkowski momenta. © 2007 Optical Society of America.
• Mansuripur, M., Kieu, K., & Mansuripur, M. -. (2007). Femtosecond laser pulse generation with a fiber taper embedded in carbon nanotube/polymer composite. Optics letters, 32(15).
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  We propose and demonstrate a new saturable absorber based on a fiber taper embedded in a carbon nanotube/polymer composite. Greater than a 10% reduction in absorption (due to saturation) is directly measured for our saturable absorber. Using an embedded fiber-taper saturable absorber, we built an all-fiber mode-locked ring laser, which produces 594 fs/1.7 nJ pulses with a repetition rate of 13.3 MHz.
• Mansuripur, M., Kieu, K., & Mansuripur, M. -. (2007). Fiber laser using a microsphere resonator as a feedback element. Optics letters, 32(3).
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  We show that a glass microsphere resonator can be used as a wavelength-selective mirror in fiber lasers. Due to their high quality factor (Q approximately 10(8)), microsphere resonators possess a narrow reflection bandwidth. This feature enables construction of single-frequency fiber lasers even when the laser cavity is long. Nonlinear effects (such as stimulated Raman lasing) were also observed in our setup at relatively low pump powers.
• Visscher, K., Skinner, G. M., & Mansuripur, M. (2007). Biocompatible Writing of Data into DNA. Journal of Bionanoscience, 1(1), 17-21. doi:10.1166/jbns.2007.005
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  A simple DNA-based data storage scheme is demonstrated in which information is written using "addressing" oligonucleotides. In contrast to other methods that allow arbitrary code to be stored, the resulting DNA is suitable for downstream enzymatic and biological processing. This capability is crucial for DNA computers, and may allow for a diverse array of computational operations to be carried out using this DNA. Although here we use gel-based methods for information readout, we also propose more advanced methods involving protein/DNA complexes and atomic force microscopy/nano-pore schemes for data readout.
• Zakharian, A. R., Xie, Y., Moloney, J. V., & Mansuripur, M. (2007). Bloch mode analysis of transmission through periodic slit arrays in finite thickness metallic slabs. Plasmonics, 6641. doi:10.1117/12.733447
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  Abstract . The Bloch modes of a periodic slit array in a metallic slab are identified, then used to investigate the transmission of light through sub-wavelength slits residi ng in a finite-thickness slab. Specifically, the Bloch mode method is used here to study Fabry-Perot-like resonances within individual slits, in conjunction with the onset of surface plasmon polariton (SPP) resonances and in the vicinity of the Wood anomalies. Although the results largely agree with our earlier numerical simulations obtained with the Finite-Difference-Time-Domain (FDTD) method, there are indications that the FDTD method has difficulty with convergence at an d around resonances; the points of agreement and disagreement between the two methods are discussed in the present paper. When the period p of the slit array is comparable to (or somewhat below) the incident wavelength  o , the Bloch mode method requires only the 10-20 lowe st-order modes of the slit array to achieve stable solutions; we find the Bloch mode method to be an effective tool fo r studying dielectric-filled apertures in highly conductive hosts.
• Mansuripur, M., & Kieu, K. Q. (2006). Biconical Fiber Taper Sensors. IEEE Photonics Technology Letters, 18(21), 2239-2241. doi:10.1109/lpt.2006.884742
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  We present several simple sensitive fiber-optics-based sensors that utilize a biconical fiber taper. A displacement sensor with 100-nm accuracy, a temperature monitor with sensitivity DeltaT~1degC, and a refractive-index sensor capable of measuring Deltan~1.42times10-5 are demonstrated using tapers made from a standard single-mode fiber
• Mansuripur, M., Kieu, K., & Mansuripur, M. -. (2006). Active Q switching of a fiber laser with a microsphere resonator. Optics letters, 31(24).
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  We propose and demonstrate an active Q-switched fiber laser using a high-Q microsphere resonator as the Q-switching element. The laser cavity consists of an Er-doped fiber as the gain medium, a glass microsphere reflector (coupled through a fiber taper) at one end of the cavity, and a fiber Bragg grating reflector at the other end. The reflectivity of the microsphere is modulated by changing the gap between the microsphere and the fiber taper. Active Q switching is realized by oscillating the microsphere in and out of contact with the taper. Using this novel technique, we have obtained giant pulses (maximum peak power approximately 102 W, duration approximately 160 ns) at a low pump-power threshold (approximately 3 mW).
• Mansuripur, M., Kieu, K., & Mansuripur, M. -. (2006). Tuning of fiber lasers by use of a single-mode biconic fiber taper. Optics letters, 31(16).
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  We report a novel scheme to build a compact, tunable fiber laser. The tuning mechanism is based on the transmission property of a single-mode biconic fiber taper. While pulling the taper, we observe oscillations in the transmitted optical power that are due primarily to interference between a pair of excited modes within the tapered region, which are eventually coupled into the unstretched single-mode fiber at the end of the taper. A similar mechanism causes the modulation of the transmitted optical spectrum after the taper has been pulled and stabilized. It is this spectral modulation by the taper that is exploited here to control the wavelength of a fiber laser. The modulation can be adjusted by stretching the taper, thus enabling the tuning of the laser wavelength. We have built a 32 mW Er-doped tunable ring fiber laser with a continuous tuning range of over 20 nm and a signal-to-noise ratio of better than 45 dB over the entire tuning range; our output power is limited only by the available pump power.
• Mansuripur, M., Kieu, K., Narumi, K., & Mansuripur, M. -. (2006). Investigation of crystallization and amorphization dynamics of phase-change thin films by subnanosecond laser pulses. Applied optics, 45(30).
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  We report experimental results on amorphization and crystallization dynamics of reversible phase-change (PC) thin-film samples, GeSbTe and GeBiTe, for optical disk data storage. The investigation was conducted with subnanosecond laser pulses using a pump-and-probe configuration. Amorphization of the crystalline films could be achieved with a single subnanosecond laser pulse; the amorphization dynamics follow closely the temperature kinetics induced in the irradiated spot. As for crystallization of the samples initially in the amorphous state, a single subnanosecond pulse was found to be insufficient to fully crystallize the irradiated spot, but we could crystallize the PC film (in the area under the focused spot) by applying multiple short pulses. Our multipulse studies reveal that the GeSbTe crystallization is dominated by the growth of nuclei whose initial formation is slow but, once formed, their subsequent growth (under a sequence of subnanosecond pulses) happens quickly. In the case of GeBiTe samples, the crystalline nuclei appear to be present in the material initially, as they grow immediately upon illumination with laser pulses. Whereas our amorphous GeSbTe samples required approximately 200 pulses for full crystallization, for the GeBiTe samples approximately 15 pulses sufficed.
• Mansuripur, M., Xie, Y., Zakharian, A. R., Moloney, J. V., & Mansuripur, M. -. (2006). Optical transmission at oblique incidence through a periodic array of sub-wavelength slits in a metallic host. Optics express, 14(22).
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  Using the Bloch modes of a periodic, semi-infinite array of slits in a metallic host, we study the transmission of obliquely incident plane-waves through sub-wavelength slits. Matching the tangential E- and H-fields at the entrance facet of the periodic structure yields the complex amplitudes of the various Bloch modes, which exist and propagate within the slit array independently of each other. The computational scheme is robust, convergence is rapid, and a good match at the boundaries is obtained in every case. The regions examined in some detail include the vicinity of the Wood anomaly (where new diffraction orders appear/disappear on the horizon), the neighborhood of a point where surface plasmon polaritons (SPPs) are excited, and an ordinary situation in which the incidence angle is far from the angles that invoke Wood's anomaly or cause the excitation of SPPs. Field distributions and energy flow diagrams in and around the slits reveal the existence of transmission minima (and reflection maxima) at incidence angles associated with the excitation of SPPs.
• Peyghambarian, N., Polynkin, P., Polynkin, A., Peyghambarian, N., Panasenko, D., Moloney, J. V., & Mansuripur, M. (2006). All-fiber passively mode-locked laser oscillator at 1.5 microm with watts-level average output power and high repetition rate.. Optics letters, 31(5), 592-4. doi:10.1364/ol.31.000592
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  We report on a passively mode-locked all-fiber laser oscillator at 1.5 microm based on heavily doped phosphate-glass active fiber. An active fiber only 20 cm long is sufficient to produce as much as 2.4 W of average output power directly from the oscillator. The width of the mode-locked pulses varies from 8 ps at the lowest output power in the mode-locked state to 44 ps at the highest power. Our picosecond laser oscillator features a high repetition rate of 95 MHz and high peak pulse power of approximately 540 W. The oscillator combines the convenience of all-fiber construction with power performance that was previously achievable only with mode-locked bulk-optic laser oscillators or more complex systems involving fiber amplifiers.
• Yoda, H., Polynkin, P., & Mansuripur, M. (2006). Beam quality factor of higher order modes in a step-index fiber. Journal of Lightwave Technology, 24(3), 1350-1355.
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  Abstract: The beam quality factor (or M2-parameter) for linearly polarized (LP)-modes of a step-index fiber is calculated in a closed form, as a function of the fiber V-number. It is shown that M2 sharply peaks for all fiber modes when they are close to cutoff. Particularly simple expressions are derived in the limit V → ∞. Two practically important coherent superpositions of modes are considered for which the degree of degradation of the beam quality due to the higher order mode content is calculated. The reported results can be useful for designing large-core high-power fiber lasers, amplifiers, and fiber-based beam delivery systems, when preservation of the spatial beam quality is important. © 2006 IEEE.
• Zakharian, A. R., Xie, Y., Moloney, J. V., & Mansuripur, M. (2006). Bloch-mode coupling to analyze periodic slits in metallic film. Nanophotonics. doi:10.1364/nano.2006.nfa5
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  We use Bloch modes to study the interaction between light and periodic structures by matching the tangential fields at the air-grating interface. Wood and surface plasmon anomalies are successfully predicted by this method.
• Berry, M. V., Jeffrey, M. R., & Mansuripur, M. (2005). Orbital and spin angular momentum in conical diffraction. Journal of Optics A: Pure and Applied Optics, 7(11), 685-690.
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  Abstract: The angular momentum Jinc of a light beam can be changed by passage through a slab of crystal. When the beam is incident along the optic axis of a biaxial crystal, which may also possess optical activity (chirality), the final angular momentum J can have both orbital (Jorb) and spin (Jsp) contributions, which we calculate paraxially exactly for arbitrary biaxiality and chirality and initially uniformly polarized beams with circular symmetry. For the familiar special case of a non-chiral crystal with fully developed conical-refraction rings, J is purely orbital and equal to Jinc/2, reflecting an interesting singularity structure in the beam. Explicit formulas and numerical computations are presented for a Gaussian incident beam. The change in angular momentum results in a torque on the crystal, along the axis of the incident beam. An additional, much larger, torque, about an axis lying in the slab, arises from the offset of the cone of conical refraction relative to the incident beam. © 2005 IOP Publishing Ltd.
• Kaneda, Y., Temyanko, V. L., Wu, J., Temyanko, V. L., Spiegelberg, C., Schulzgen, A., Qiu, T., Polynkin, P., Polynkin, A., Peyghambarian, N., Moloney, J. V., Mansuripur, M., Mafi, A., Luo, T., Li, L., Kaneda, Y., Jiang, S., Geng, J., & Chavez, A. (2005). Chip-Scale, High Power Microstructure Fiber Laser. MRS Proceedings, 883(1), 65-70. doi:10.1557/proc-883-ff2.1
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  Compact, robust, high power fiber lasers have been demonstrated. In fiber lasers of only a few cm length we obtained up to 10 W of cw output power, diffraction limited beam profiles at 4 W cw operation, 1.6 W output with single frequency operation, and more than 150 mW output with a spectral linewidth of a few kHz. The potential of active microstructured fibers for further improvements in fiber laser performance has been shown. We also demonstrated Q-switching and mode-locking of these compact fiber lasers.
• Khulbe, P. K., Mansuripur, M., & Gruener, R. (2005). DNA translocation through α -hemolysin nanopores with potential application to macromolecular data storage. Journal of Applied Physics, 97(10).
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  Abstract: Digital information can be encoded in the building-block sequence of macromolecules, such as RNA and single-stranded DNA. Methods of "writing" and "reading" macromolecular strands are currently available, but they are slow and expensive. In an ideal molecular data storage system, routine operations such as write, read, erase, store, and transfer must be done reliably and at high speed within an integrated chip. As a first step toward demonstrating the feasibility of this concept, we report preliminary results of DNA readout experiments conducted in miniaturized chambers that are scalable to even smaller dimensions. We show that translocation of a single-stranded DNA molecule (consisting of 50 adenosine bases followed by 100 cytosine bases) through an ion channel yields a characteristic signal that is attributable to the two-segment structure of the molecule. We also examine the dependence of the translocation rate and speed on the adjustable parameters of the experiment. © 2005 American Institute of Physics.
• Mansuripur, M. (2005). Angular momentum of circularly polarized light in dielectric media.. Optics express, 13(14), 5315-24. doi:10.1364/opex.13.005315
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  A circularly polarized plane-wave is known to have no angular momentum when examined through Maxwell's equations. This, however, contradicts the experimentally observed facts, where finite segments of plane waves are known to be capable of imparting angular momentum to birefringent platelets. Using a superposition of four plane-waves propagating at slightly different angles to a common direction, we derive an expression for the angular momentum density of a single plane-wave in the limit when the propagation directions of the four beams come into alignment. We proceed to use this four-beam technique to analyze the conservation of angular momentum when a plane-wave enters a dielectric slab from the free space. The angular momentum of the beam is shown to decrease upon entering the dielectric medium, by virtue of the fact that the incident beam exerts a torque on the slab surface at the point of entry. When the beam leaves the slab, it imparts an equal but opposite torque to the exit facet, thus recovering its initial angular momentum upon re-emerging into the free-space. Along the way, we derive an expression for the outward-directed force of a normally incident, finite-diameter beam on a dielectric surface; the possible relationship between this force and the experimentally observed bulging of a liquid surface under intense illumination is explored.
• Mansuripur, M. (2005). Information storage and retrieval using macromolecules as media. 2005 Proceedings of the 4th ASME Conference on Integrated Nanosystems: Design, Synthesis, and Applications, 33-34.
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  Abstract: To store information at extremely high-density and data-rate, we propose to adapt, integrate, and extend the techniques developed by chemists and molecular biologists for the purpose of manipulating biological and other macromolecules. Copyright © 2005 by ASME.
• Mansuripur, M. (2005). Radiation pressure and the distribution of electromagnetic force in dielectric media. Proceedings of SPIE - The International Society for Optical Engineering, 5930, 1-7.
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  Abstract: A detailed distribution of the force of electromagnetic radiation in and around dielectric media can be obtained by a direct application of the Lorentz law of force in conjunction with Maxwell's equations. We develop a theory of the force exerted by a focused light beam on the free surface as well as within the volume of a transparent dielectric medium. Although the medium can be either solid or liquid, here we emphasize the application of the formulas to liquids since, in principle at least, surface deformations and liquid motions are measurable. Our theory predicts that, upon entering the liquid from the free space, the beam of light exerts an outward vertical force on the entrance surface that tends to produce a localized bulge. This surface force, however, is much weaker than that predicted by prevailing theories and, in contrast to current beliefs, is found to depend on the polarization state of the incident beam. Within the volume of the liquid we predict that the forces of radiation tend to create four counter-rotating vortices at the four corners of the focused spot; the sense of rotation within these vortices depends on the direction of the incident polarization. These striking departures from conventional wisdom with regard to the force of radiation arise from a revision in the form of the Lorentz law as applied to the bound charges/currents within a dielectric medium.
• Mansuripur, M. (2005). Radiation pressure and the linear momentum of light in dispersive dielectric media. Optics Express, 13(6), 2245-2250.
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  PMID: 19495112;Abstract: We derive an exact expression for the radiation pressure of a quasi- monochromatic plane wave incident from the free space onto the flat surface of a semi-infinite dielectric medium. In order to account for the total optical momentum (incident plus reflected) that is transferred to the dielectric, the mechanical momentum acquired by the medium must be added to the rate of flow of the electromagnetic momentum (the so-called Abraham momentum) inside the dielectric. We confirm that the electromagnetic momentum travels with the group velocity of light inside the medium. The photon drag effect in which the photons captured in a semiconductor appear to have the Minkowski momentum is explained by analyzing a model system consisting of a thin absorptive layer embedded in a transparent dielectric. © 2005 Optical Society of America.
• Mansuripur, M., Polynkin, P., Polynkin, A., Peyghambarian, N., & Mansuripur, M. -. (2005). Evanescent field-based optical fiber sensing device for measuring the refractive index of liquids in microfluidic channels. Optics letters, 30(11).
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  We report a simple optical sensing device capable of measuring the refractive index of liquids propagating in microfluidic channels. The sensor is based on a single-mode optical fiber that is tapered to submicrometer dimensions and immersed in a transparent curable soft polymer. A channel for liquid analyte is created in the immediate vicinity of the taper waist. Light propagating through the tapered section of the fiber extends into the channel, making the optical loss in the system sensitive to the refractive-index difference between the polymer and the liquid. The fabrication process and testing of the prototype sensing devices are described. The sensor can operate both as a highly responsive on-off device and in the continuous measurement mode, with an estimated accuracy of refractive-index measurement of approximately 5 x 10(-4).
• Mansuripur, M., Watabe, K., Polynkin, P., & Mansuripur, M. -. (2005). Optical pump-and-probe test system for thermal characterization of thin metal and phase-change films. Applied optics, 44(16).
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  A single-shot optical pump-and-probe test system is reported. The system is designed for thermal characterization of thin-film samples that can change their phase state under the influence of a short and intense laser pulse on a subnanosecond time scale. In combination with numerical analysis, the system can be used to estimate thermal constants of thin films, such as specific heat and thermal conductivity. In-plane and out-of plane thermal conductivity can be estimated independently. The system is intended for use in research on optical data storage and material processing with pulsed laser light. The system design issues are discussed. As application examples, we report on using the system to study thermal dynamics in two different thin-film samples: a gold film on a glass substrate (a single-phase system) and the quadrilayer phase-change stack typical in optical data-storage applications.
• Polynkin, A., Polynkin, P., Mansuripur, M., & Peyghambarian, N. (2005). Single-frequency fiber ring laser with 1 W output power at 1.5 μm. Optics Express, 13(8), 3179-3184.
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  PMID: 19495217;Abstract: We report a single-frequency fiber laser with 1 W output power at 1.5 μm which is to our knowledge, five times the highest power from a single-frequency fiber laser reported to-date. The short unidirectional ring cavity approach is used to eliminate the spatial gain hole-burning associated with the standing-wave laser designs. A heavily-doped phosphate fiber inside the ring resonator serves as the active medium of the laser. Up to 700 mW of output power, the longitudinal mode hops have been completely eliminated by using the adjustable coupled-cavity approach. At higher power levels, the laser still oscillates at a single longitudinal mode, but with infrequent mode hops that occur at a rate of few hops per minute. Compared to the Watt-level single-frequency amplified sources, our approach is simpler and offers better noise performance. © 2005 Optical Society of America.
• Polynkin, A., Polynkin, P., Schülzgen, A., Mansuripur, M., & Peyghambarian, N. (2005). Watts-level, short all-fiber laser at 1.5 μm with a large core and diffraction-limited output via intracavity spatial-mode filtering. Optics Letters, 30(4), 403-405.
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  PMID: 15762442;Abstract: We report over 2 W of single spatial-mode output power at 1.5 μm from an 8-cm-long, large-core phosphate fiber laser. The fiber has a numerical aperture of =0.17 and a 25-μm-wide core, heavily doped with 1% Er+3 and 8% Yb+3. The laser utilizes a scalable evanescent-field-based pumping scheme and can be pumped by as many as eight individual multimode pigtailed diode laser sources at a wavelength of 975 nm. Nearly diffraction-limited laser output with a beam quality factor M2 ≃ 1.1 is achieved by use of a simple intracavity all-fiber spatial-mode filter. Both spectrally broadband and narrowband operation of the laser are demonstrated. © 2005 Optical Society of America.
• Polynkin, P., Polynkin, A., Peyghambarian, N., & Mansuripur, M. (2005). Evanescent field-based optical fiber sensing device for measuring the refractive index of liquids in microfluidic channels. Optics Letters, 30(11), 1273-1275.
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  PMID: 15981504;Abstract: We report a simple optical sensing device capable of measuring the refractive index of liquids propagating in microfluidic channels. The sensor is based on a single-mode optical fiber that is tapered to submicrometer dimensions and immersed in a transparent curable soft polymer. A channel for liquid analyte is created in the immediate vicinity of the taper waist. Light propagating through the tapered section of the fiber extends into the channel, making the optical loss in the system sensitive to the refractive-index difference between the polymer and the liquid. The fabrication process and testing of the prototype sensing devices are described. The sensor can operate both as a highly responsive on-off device and in the continuous measurement mode, with an estimated accuracy of refractive-index measurement of ∼5×10-4. © 2005 Optical Society of America.
• Watabe, K., Polynkin, P., & Mansuripur, M. (2005). Optical pump-and-probe test system for thermal characterization of thin metal and phase-change films. Applied Optics, 44(16), 3167-3173.
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  PMID: 15943249;Abstract: A single-shot optical pump-and-probe test system is reported. The system is designed for thermal characterization of thin-film samples that can change their phase state under the influence of a short and intense laser pulse on a subnanosecond time scale. In combination with numerical analysis, the system can be used to estimate thermal constants of thin films, such as specific heat and thermal conductivity. In-plane and out-of plane thermal conductivity can be estimated independently. The system is intended for use in research on optical data storage and material processing with pulsed laser light. The system design issues are discussed. As application examples, we report on using the system to study thermal dynamics in two different thin-film samples: a gold film on a glass substrate (a single-phase system) and the quadrilayer phase-change stack typical in optical data-storage applications. © 2005 Optical Society of America.
• Giridhar, M. S., Seong, K., Schülzgen, A., Khulbe, P., Peyghambarian, N., & Mansuripur, M. (2004). Femtosecond pulsed laser micromachining of glass substrates with application to microfluidic devices. Applied Optics, 43(23), 4584-4589.
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  PMID: 15376436;Abstract: We describe a technique for surface and subsurface micromachining of glass substrates by using tightly focused femtosecond laser pulses at a wavelength of 1660 nm. A salient feature of pulsed laser micromachining is its ability to drill subsurface tunnels into glass substrates. To demonstrate a potential application of this micromachining technique, we fabricate simple microfluidic structures on a glass plate. The use of a cover plate that seals the device by making point-to-point contact with the flat surface of the substrate is necessary to prevent the evaporation of liquids in open channels and chambers. Methods for protecting and sealing the micromachined structures for microfluidic applications are discussed. © 2004 Optical Society of America.
• Mansuripur, M. (2004). Radiation pressure and the linear momentum of the electromagnetic field. Optics Express, 12(22), 5375-5401.
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  PMID: 19484099;Abstract: The force of the electromagnetic radiation on material objects by a direct application of the Lorentz law of classical electrodynamics was derived. The derivation is straightforward in the case of solid metals and solid dielectrics. For metallic mirrors, the contribution to the radiation pressure of the electrical charge density was separated from that of the current density of the conduction electrons. In the case of dielectric media, the forces experienced by bound charges and currents were examined, and the contribution of each of the radiation pressure was determined.
• Mansuripur, M., & Khulbe, P. (2004). Macro-molecular data storage with petabyte/cm ³ density, highly parallel read/write operations, and genuine 3D storage capability. Proceedings of SPIE - The International Society for Optical Engineering, 5380, 272-282.
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  Abstract: Digital information can be encoded in the building-block sequence of macromolecules, such as RNA and single-stranded DNA. Methods of "writing" and "reading" macromolecular strands are currently available, but they are slow and expensive. In an ideal molecular data storage system, routine operations such as write, read, erase, store, and transfer must be done reliably and at high speed within an integrated chip. As a first step toward demonstrating the feasibility of this concept, we report preliminary results of DNA readout experiments conducted in miniaturized chambers that are scalable to even smaller dimensions. We show that translocation of a single-stranded DNA molecule (consisting of 50 adenosine bases followed by 100 cytosine bases) through an ion-channel yields a characteristic signal that is attributable to the 2-segment structure of the molecule. We also examine the dependence of the rate and speed of molecular translocation on the adjustable parameters of the experiment.
• Mansuripur, M., Giridhar, M. S., Seong, K., Schülzgen, A., Khulbe, P., Peyghambarian, N., & Mansuripur, M. -. (2004). Femtosecond pulsed laser micromachining of glass substrates with application to microfluidic devices. Applied optics, 43(23).
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  We describe a technique for surface and subsurface micromachining of glass substrates by using tightly focused femtosecond laser pulses at a wavelength of 1660 nm. A salient feature of pulsed laser micromachining is its ability to drill subsurface tunnels into glass substrates. To demonstrate a potential application of this micromachining technique, we fabricate simple microfluidic structures on a glass plate. The use of a cover plate that seals the device by making point-to-point contact with the flat surface of the substrate is necessary to prevent the evaporation of liquids in open channels and chambers. Methods for protecting and sealing the micromachined structures for microfluidic applications are discussed.
• Mansuripur, M., Kosterin, A., Temyanko, V., Fallahi, M., & Mansuripur, M. -. (2004). Tapered fiber bundles for combining high-power diode lasers. Applied optics, 43(19).
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  Tapered fiber bundles are often used to combine the output power of several semiconductor lasers into a multimode optical fiber for the purpose of pumping fiber lasers and amplifiers. It is generally recognized that the brightness of such combiners does not exceed the brightness of the individual input fibers. We report that the brightness of the tapered fibers (and fiber bundles) depends on both the taper ratio and the mode-filling properties of the beams launched into the individual fibers. Brightness, therefore, can be increased by selection of sources that fill a small fraction of the input fiber's modal capacity. As proof of concept, we present the results of measurements on tapered fiber-bundle combiners having a low-output étendue. Under low mode-filling conditions per input multimode fiber (i.e., fraction of filled modes < or =0.29), we report brightness enhancements of 8.0 dB for 19 x 1 bundles, 6.7 dB for 7 x 1 bundles, and 4.0 dB for 3 x 1 combiners. Our measured coupling efficiency variations of approximately 1%-2% among the various fibers in a given bundle confirm the uniformity and quality of the fabricated devices.
• Mansuripur, M., Peng, C., & Mansuripur, M. -. (2004). Amorphization induced by subnanosecond laser pulses in phase-change optical recording media. Applied optics, 43(22).
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  We have investigated the dynamics of amorphization induced in phase-change optical recording media by focused laser pulses of subnanosecond duration. We initiated localized amorphism by using a focused laser beam to melt the phase-change material and completed the change by rapid cooling by means of thermal diffusion. These studies were conducted by use of real-time reflectivity measurements with a pump-and-probe technique in which both pump and probe pulses had a duration of approximately 510 ps. Our transient-reflectivity measurements indicate that the process that leads to amorphism has three distinct stages, namely, rapid melting, solidification, and slow relaxation.
• Peng, C., & Mansuripur, M. (2004). Amorphization induced by subnanosecond laser pulses in phase-change optical recording media. Applied Optics, 43(22), 4367-4375.
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  PMID: 15298410;Abstract: We have investigated the dynamics of amorphization induced in phase-change optical recording media by focused laser pulses of subnanosecond duration. We initiated localized amorphism by using a focused laser beam to melt the phase-change material and completed the change by rapid cooling by means of thermal diffusion. These studies were conducted by use of real-time reflectivity measurements with a pump-and-probe technique in which both pump and probe pulses had a duration of ∼510 ps. Our transient-reflectivity measurements indicate that the process that leads to amorphism has three distinct stages, namely, rapid melting, solidification, and slow relaxation. © 2004 Optical Society of America.
• Polynkin, P., Temyanko, V., Mansuripur, M., & Peyghambarian, N. (2004). Efficient and scalable side pumping scheme for short high-power optical fiber lasers and amplifiers. IEEE Photonics Technology Letters, 16(9), 2024-2026.
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  Abstract: A new and simple method of pumping short high-power optical fiber lasers and amplifiers is described. In our approach, several passive coreless optical fibers are brought into direct contact alongside a single rare-earth doped active fiber which constitutes the active medium of the laser (amplifier). Pump light is delivered through the passive coreless fibers and penetrates into the active fiber via evanescent field coupling. To enhance the pump absorption in the gain medium, high-order spatial modes are excited in the pump delivery fibers, and an active fiber with high concentration of the dopant ions is used. As a demonstration of the viability of our approach, test results are reported on a 12-cm-long Er+3-Yb+3 codoped phosphate glass fiber laser. The laser output reaches 5 W using 23-W pumping into six coreless fibers. Above threshold, the laser has ∼24% optical-to-optical conversion efficiency (with ∼64% being the theoretical maximum). The linearity of the input-output characteristic for the laser suggests that the output power can be scaled up by applying higher pump power. © 2004 IEEE.
• Vallius, T., Turunen, J., Mansuripur, M., & Honkanen, S. (2004). Transmission through single subwavelength apertures in thin metal films and effects of surface plasmons. Journal of the Optical Society of America A: Optics and Image Science, and Vision, 21(3), 456-463.
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  PMID: 15005412;Abstract: The existing analyses on extraordinary optical transmission through apertures on a metal screen have been carried out assuming perfect conductivity or by examining arrays of closely spaced holes with subwavelength dimensions. We present an electromagnetic analysis of a single hole (modeled by use of an array of distant holes) in a finitely conducting metal membrane, applying no approximations. We demonstrate that finite conductivity is not of remarkable importance with small hole-diameter-to-wavelength ratios in the absence of strong resonances. However, if the angle of incidence of a plane wave is such that surface plasmons are excited, substantial enhancement of the transmittance can be observed, and the effect of finite conductivity will no longer be negligible. Our analysis also reveals that transmission of small apertures in highly conducting membranes can be described by approximate analytical formulas if surface waves are not excited, but with poor conductors the full electromagnetic analysis should be applied. © 2004 Optical Society of America.
• Watabe, K., Polynkin, P., & Mansuripur, M. (2004). Behavior of GeSbTeBi phase-change optical recording media under sub-nanosecond pulsed laser irradiation. Proceedings of SPIE - The International Society for Optical Engineering, 5380, 342-350.
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  Abstract: Reflectivity variations during phase-transition between amorphous and crystalline states of a Bi-doped GeTe-Sb2Te3 pseudo-binary compound film is investigated with sub-nanosecond laser pulses using a pump-and-probe technique. We also use a two-laser static tester to estimate the onset time of crystallization under a 2.0-μs-pulse excitation. Experimental results indicate that the formation of a melt-quenched amorphous mark is completed in about one nanosecond, but crystalline mark formation on an as-deposited amorphous region requires several hundred nanoseconds. Simple arguments based on heat diffusion are used to explain the time scale of amorphization and the threshold for creation of a burned-out hole on the phase-change film.
• Watabe, K., Polynkin, P., & Mansuripur, M. (2004). Behavior of GeSbTeBi phase-change optical recording media under subnanosecond pulsed laser irradiation. Applied Optics, 43(20), 4033-4040.
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  PMID: 15285095;Abstract: We investigated the variations in reflectivity during the phase transition between amorphous and crystalline states of a Bi-doped GeTe-Sb 2Te3 pseudobinary compound film with subnanosecond laser pulses, using a pump-and-probe technique. We also used a two-laser static tester to estimate the onset time of crystallization under 2.0-μ.s pulse excitation. Experimental results indicate that the formation of a melt-quenched amorphous mark is completed in ∼1 ns, but that crystalline mark formation on an as-deposited amorphous region requires several hundred nanoseconds. Simple arguments based on heat diffusion are used to explain the time scale of amorphization and the threshold for creation of a burned-out hole in the phase-change film. © 2004 Optical Society of America.
• Mansuripur, M., Euteneuer, A., Fernandez, D., & Medower, B. (2003). Media characterization methods for optical data storage. Conference on Lasers and Electro-Optics Europe - Technical Digest, 741-.
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  Abstract: We have developed a two-laser media tester to investigate the recording dynamics in phase-change (PC), magneto-optical (MO), and dye-polymer disks as well as in other media samples. We have used these and many similar measurements to elucidate the behavior of writable and rewritable media of optical data storage. In addition to gaining insight into the dynamics of crystallization, melting, melt-quenched amorphization, (PC media), and magnetization reversal (MO media), we have used these techniques to extract information about thermal constants of the active layer as well as the encapsulating dielectric and metal layers used in commercial optical disks. © 2003 IEEE.
• Mansuripur, M., Khulbe, P. K., Kuebler, S. M., Perry, J. W., Giridhar, M. S., Erwin, J. K., Seong, K., Marder, S., & Peyghambarian, N. (2003). Information Storage and Retrieval using Macromolecules as Storage Media. Proceedings of SPIE - The International Society for Optical Engineering, 5069, 231-243.
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  Abstract: The development of a data storage device by using macromolecules as the storage media was discussed. Micro-fluidic techniques were used for transporting the molecules through various chambers within a small, integrated chip. A method of macromolecular readout by translocation through nano-pore was also described.
• Fischer, G. M., Medower, B., Revay, R., & Mansuripur, M. (2002). Thermal properties and crystallization dynamics of a phase-change alloy for write-once optical data storage. Applied Optics, 41(10), 1998-2007.
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  PMID: 11936803;Abstract: Using a two-laser static tester, we measured the crystallization temperature and the thermal conductivity of a phase-change alloy thin film used in write-once-read-many media of optical data storage. The experimental technique, in general, and the calibration procedures, in particular, are described. The measurement results are used as entry points into numerical calculations that ultimately yield estimates of the material parameters. Valuable information about the dynamics of mark formation (i.e., localized crystallization) in amorphous phase-change alloy films is obtained from the observed variations of the sample reflectance under short-pulse and long-pulse recording conditions. The dependence of these reflectance variations on the laser pulse power has also been investigated. © 2002 Optical Society of America.
• Khulbe, P. K., Hurst, T., & Mansuripur, M. (2002). Temperature-dependence of optical constants in phase-change media. Proceedings of SPIE - The International Society for Optical Engineering, 4342, 103-107.
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  Abstract: The temperature-dependence of optical constants in phase-change media was discussed. The reflectivity variations of the phase-change media of optical recording were observed. The reflectivity changed slightly upon the application of a weak laser pulse, returning to its initial value at the end of the pulse. This behavior was shown to be due to the temperature-dependence of the optical constants of the phase-change layer.
• Khulbe, P. K., Hurst, T., Horie, M., & Mansuripur, M. (2002). Crystallization behavior of Ge-doped eutectic Sb₇₀Te₃₀ films in optical disks. Applied Optics, 41(29), 6220-6229.
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  PMID: 12389992;Abstract: We report laser-induced crystallization behavior of binary Sb-Te and ternary Ge-doped eutectic Sb70Te30 thin film samples in a typical quadrilayer stack as used in phase-change optical disk data storage. Several experiments have been conducted on a two-laser static tester in which one laser operating in pulse mode writes crystalline marks on amorphous film or amorphous marks on crystalline film, while the second laser operating at low-power cw mode simultaneously monitors the progress of the crystalline or amorphous mark formation in real time in terms of the reflectivity variation. The results of this study show that the crystallization kinetics of this class of film is strongly growth dominant, which is significantly different from the crystallization kinetics of stochiometric Ge-Sb-Te compositions. In Sb-Te and Ge-doped eutectic Sb70Te30 thin-film samples, the crystallization behavior of the two forms of amorphous states, namely, as-deposited amorphous state and melt-quenched amorphous state, remains approximately same. We have also presented experiments showing the effect of the variation of the Sb/Te ratio and Ge doping on the crystallization behavior of these films. © 2002 Optical Society of America.
• Liang, R., Carriere, J., & Mansuripur, M. (2002). Intensity, polarization, and phase information in optical disk systems. Applied Optics, 41(8), 1565-1573.
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  PMID: 11928756;Abstract: Digital information in optical data storage systems can be encoded in the intensity, in the polarization state, or in the phase of a carrier laser beam. Intensity modulation is achieved at the surface of the storage medium either through destructive interference from surface-relief features (e.g., CD or DVD pits) or through reflectivity variations (e.g., alteration of optical constants of phase-change media). Magneto-optical materials make use of the polar magneto-optical Kerr effect to produce polarization modulations of the focused beam reflected from the storage medium. Both surface-relief structures and material-property variations can create, at the exit pupil of the objective lens of the optical pickup, a phase modulation (this, in addition to any intensity or polarization modulation or both). Current optical data storage systems do not make use of this phase information, whose recovery could potentially increase the strength of the readout signal. We show how all three mechanisms can be exploited in a scanning optical microscope to reconstruct the recorded (or embedded) data patterns on various types of optical disk. © 2002 Optical Society of America.
• Liang, R., Peng, C., Nagata, K., Daly-Flynn, K., & Mansuripur, M. (2002). Optical characterization of multilayer stacks for phase-change media. Proceedings of SPIE - The International Society for Optical Engineering, 4342, 134-145.
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  Abstract: We report results of measurements of the optical constants of the dielectric layer (ZnS-SiO2), reflecting layer (aluminum-chromium alloy), and phase-change layer (GeSbTe, AgInSbTe) used as the media of phase-change optical recording. The refractive index n and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories.
• Liang, R., Peng, C., Nagata, K., Daly-Flynn, K., & Mansuripur, M. (2002). Optical characterization of multilayer stacks used as phase-change media of optical disk data storage. Applied Optics, 41(2), 370-378.
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  PMID: 11899276;Abstract: We report results of measurements of the optical constants of the dielectric layer (ZnS-SiO2), reflecting layer (aluminum-chromium alloy), and phase-change layer (GeSbTe, AgInSbTe) used as the media of phase-change optical recording. The refractive index n and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories. © 2002 Optical Society of America.
• Mansuripur, M. (2002). DNA, human memory, and the storage technology of the 21^st century. Proceedings of SPIE - The International Society for Optical Engineering, 4342, 1-29.
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  Abstract: A study of biological data storage technology was carried out. Various approaches to research and development in biological data storage were also studied. Nature has evolved certain biological systems that are capable of processing and storage of information far more efficiently than any man-made device.
• Mansuripur, M. (2002). Dependence of capacity on media noise in data storage systems. Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 41(3 B), 1638-1642.
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  Abstract: The storage capacity of a medium, be it a one-dimensional wire, a two-dimensional platter, or a three-dimensional cube, ultimately depends on the intrinsic signal-to-noise ratio of the storage medium. The recording mechanism may be assumed to be error-free in the sense that any region of the medium, no matter how small, can be repeatedly and reliably set to one of two physically distinct states, 0 and 1. Also, the readout mechanism can be assumed to have unlimited resolution, in the sense that an arbitrarily small probe-tip can explore the storage medium and translate its local physical state into a real-valued binary signal of magnitude S0 or S1 in units of, say, volts. As far as the intrinsic storage capacity of the medium is concerned, the data-transfer rate and any time-dependent noise contributions to the readout signal can be made irrelevant. This is achieved by slowing down the readout process to allow integration over long intervals of time, thereby reducing the time-dependent component of noise to a negligibly small value. The only noise source that needs serious consideration, therefore, is the media noise, which manifests itself in the fluctuations of the readout signal observed when the probe-tip scans the medium, moving from one location to another to reveal the local state of the medium in its output signal, S0 or S1. The fundamental assumptions of this paper, are: (i) the media noise is white, that is, its spatial distribution is uncorrelated; (ii) the power spectral density of the media noise is No volt2·cmd, where d is the dimensionality of the storage medium (d = 1 for a wire, d = 2 for a platter, d = 3 for a cube). The storage capacity C of the medium per unit length, area, or volume (as the case may be) is found to be proportional to the medium's intrinsic signal-to-noise ratio in accordance with the formula C = 0.059 (Si - S0)2/No in units of bits per cmd.
• Mansuripur, M. (2002). Doppler shift, stellar aberration, and convection of light by moving media. Optics and Photonics News, 13(4), 52-56.
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  Abstract: The Doppler shift, Stellar aberration and convection of light by moving media was discussed. The general formulas for all the three phenomena were derived by applying the Lorentz transformation to a plane electromagnetic wave. The plot of a plane wave propagating along the unit vector in the cartesian coordinate system was presented.
• Mansuripur, M. (2002). The uncertainty principle in classical optics. Optics and Photonics News, 13(1), 44-48.
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  Abstract: The constraints imposed by the uncertainity principle on classical optics problems was discussed. The separation of two overlapping beams of identical wavelength having slightly different propagation directions and the limits of separating co-propagating beams having slightly different wavelengths was analyzed. It was found that the two constituent composite beams continue to overlap at first, giving rise to interesting interference patterns. After a sufficient propagation distance, the beams separate and go their own ways.
• Mansuripur, M., Fischer, G. M., Medower, B., Revay, R., & Mansuripur, M. -. (2002). Thermal properties and crystallization dynamics of a phase-change alloy for write-once optical data storage. Applied optics, 41(10).
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  Using a two-laser static tester, we measured the crystallization temperature and the thermal conductivity of a phase-change alloy thin film used in write-once-read-many media of optical data storage. The experimental technique, in general, and the calibration procedures, in particular, are described. The measurement results are used as entry points into numerical calculations that ultimately yield estimates of the material parameters. Valuable information about the dynamics of mark formation (i.e., localized crystallization) in amorphous phase-change alloy films is obtained from the observed variations of the sample reflectance under short-pulse and long-pulse recording conditions. The dependence of these reflectance variations on the laser pulse power has also been investigated.
• Mansuripur, M., Khulbe, P. K., Hurst, T., Horie, M., & Mansuripur, M. -. (2002). Crystallization behavior of Ge-doped eutectic Sb70Te30 films in optical disks. Applied optics, 41(29).
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  We report laser-induced crystallization behavior of binary Sb-Te and ternary Ge-doped eutectic Sb70Te30 thin film samples in a typical quadrilayer stack as used in phase-change optical disk data storage. Several experiments have been conducted on a two-laser static tester in which one laser operating in pulse mode writes crystalline marks on amorphous film or amorphous marks on crystalline film, while the second laser operating at low-power cw mode simultaneously monitors the progress of the crystalline or amorphous mark formation in real time in terms of the reflectivity variation. The results of this study show that the crystallization kinetics of this class of film is strongly growth dominant, which is significantly different from the crystallization kinetics of stochiometric Ge-Sb-Te compositions. In Sb-Te and Ge-doped eutectic Sb70Te30 thin-film samples, the crystallization behavior of the two forms of amorphous states, namely, as-deposited amorphous state and melt-quenched amorphous state, remains approximately same. We have also presented experiments showing the effect of the variation of the Sb/Te ratio and Ge doping on the crystallization behavior of these films.
• Mansuripur, M., Liang, R., Carriere, J., & Mansuripur, M. -. (2002). Intensity, polarization, and phase information in optical disk systems. Applied optics, 41(8).
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  Digital information in optical data storage systems can be encoded in the intensity, in the polarization state, or in the phase of a carrier laser beam. Intensity modulation is achieved at the surface of the storage medium either through destructive interference from surface-relief features (e.g., CD or DVD pits) or through reflectivity variations (e.g., alteration of optical constants of phase-change media). Magneto-optical materials make use of the polar magneto-optical Kerr effect to produce polarization modulations of the focused beam reflected from the storage medium. Both surface-relief structures and material-property variations can create, at the exit pupil of the objective lens of the optical pickup, a phase modulation (this, in addition to any intensity or polarization modulation or both). Current optical data storage systems do not make use of this phase information, whose recovery could potentially increase the strength of the readout signal. We show how all three mechanisms can be exploited in a scanning optical microscope to reconstruct the recorded (or embedded) data patterns on various types of optical disk.
• Mansuripur, M., Liang, R., Peng, C., Nagata, K., Daly-Flynn, K., & Mansuripur, M. -. (2002). Optical characterization of multilayer stacks used as phase-change media of optical disk data storage. Applied optics, 41(2).
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  We report results of measurements of the optical constants of the dielectric layer (ZnS-SiO2), reflecting layer (aluminum-chromium alloy), and phase-change layer (GeSbTe, AgInSbTe) used as the media of phase-change optical recording. The refractive index n and the absorption coefficient k of these materials vary to some extent with the film thickness and with the film deposition environment. We report the observed variations of optical constants among samples of differing structure and among samples fabricated in different laboratories.
• Mansuripur, M., Peng, C., & Mansuripur, M. -. (2002). Measurement of the thermal coefficients of rewritable phase-change optical recording media. Applied optics, 41(2).
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  We describe a method to estimate the heat capacity of the substrate, the dielectric layer, and the phase-change layer of phase-change optical recording media as well as the thermal conductivity of the phase-change layer in its crystalline state. Measurements were carried out on spinning disks with the beam of light focused and locked onto the groove track. The method relies on the identification of the solid-to-liquid phase transition that occurs in the phase-change layer and takes advantage of the dependence of thermal diffusion on track velocity and irradiation time.
• Mansuripur, M., Peng, C., & Mansuripur, M. -. (2002). Partial-response signaling for phase-change optical data storage without electronic equalization. Applied optics, 41(17).
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  We describe the application of partial-response (PR) signaling in rewritable phase-change optical data storage. No electronic filter is necessary to shape the readout signal to a certain PR target. A PR-like waveform at the output of the read channel is directly achieved by optical recording. A genetic algorithm is used to optimize the parameters for writing and therefore to minimize the difference between the actual readout signal and the ideal PR waveform. With a laser wavelength of 0.66 microm and an objective lens with a numerical aperture of 0.6, four linear densities were examined: 0.4, 0.3, 0.25, and 0.2 microm/bit (without modulation). Results showed that the linear density of 0.25 microm/bit can be realized on a rewritable digital-versatile disk.
• Mansuripur, M., Xun, X., Peng, C., & Mansuripur, M. -. (2002). Estimation of thermal coefficients of magneto-optical media. Applied optics, 41(22).
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  Previously we described a method for estimating the thermal conductivity of magneto-optic recording media. The method relies on identifying the laser power that brings the maximum temperature of the TbFeCo layer to as high as the Curie temperature. We extensively use a similar method to estimate the heat capacity of a dielectric layer, a TbFeCo layer, and an aluminum alloy layer of magneto-optic recording media. Measurements are conducted on static disks with a beam of light focused on a TbFeCo layer. The method has the advantage of thermal diffusion depending on a multilayer structure and irradiation time.
• Peng, C., & Mansuripur, M. (2002). Measurement of the thermal coefficients of rewritable phase-change optical recording media. Applied Optics, 41(2), 361-369.
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  PMID: 11899275;Abstract: We describe a method to estimate the heat capacity of the substrate, the dielectric layer, and the phase-change layer of phase-change optical recording media as well as the thermal conductivity of the phase-change layer in its crystalline state. Measurements were carried out on spinning disks with the beam of light focused and locked onto the groove track. The method relies on the identification of the solid-to-liquid phase transition that occurs in the phase-change layer and takes advantage of the dependence of thermal diffusion on track velocity and irradiation time. © 2002 Optical Society of America.
• Peng, C., & Mansuripur, M. (2002). Partial-response signaling for phase-change optical data storage without electronic equalization. Applied Optics, 41(17), 3479-3486.
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  PMID: 12074520;Abstract: We describe the application of partial-response (PR) signaling in rewritable phase-change optical data storage. No electronic filter is necessary to shape the readout signal to a certain PR target. A PR-like waveform at the output of the read channel is directly achieved by optical recording. A genetic algorithm is used to optimize the parameters for writing and therefore to minimize the difference between the actual readout signal and the ideal PR waveform. With a laser wavelength of 0.66 μm and an objective lens with a numerical aperture of 0.6, four linear densities were examined: 0.4, 0.3, 0.25, and 0.2 μm/bit (without modulation). Results showed that the linear density of 0.25 μm/bit can be realized on a rewritable digital-versatile disk. © 2002 Optical Society of America.
• Xun, X., Peng, C., & Mansuripur, M. (2002). Estimation of thermal coefficients of magneto-optical media. Applied Optics, 41(22), 4596-4602.
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  PMID: 12153092;Abstract: Previously we described a method for estimating the thermal conductivity of magneto-optic recording media. The method relies on identifying the laser power that brings the maximum temperature of the TbFeCo layer to as high as the Curie temperature. We extensively use a similar method to estimate the heat capacity of a dielectric layer, a TbFeCo layer, and an aluminum alloy layer of magneto-optic recording media. Measurements are conducted on static disks with a beam of light focused on a TbFeCo layer. The method has the advantage of thermal diffusion depending on a multilayer structure and irradiation time. © 2002 Optical Society of America.
• Liang, R., Lifeng, L. i., Saito, K., & Mansuripur, M. (2001). Polarization dependence of readout signals from periodic one-dimensional arrays of magnetic domains in magneto-optical media and crystalline-amorphous line pairs in phase-change media of optical recording. Applied Optics, 40(14), 2323-2330.
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  PMID: 18357242;Abstract: Polarization dependence of signals from periodic one-dimensional arrays of magnetic domains in magneto-optical (MO) media and crystalline domains in amorphous phase-change (PC) media has been studied by theoretical calculation and experiment. The MO signal in the small-period regime depends on the direction of incident polarization. The relative strength of the E∥ and E⊥ signals changes depending on the period of the pattern, the wavelength of the light, and the numerical aperture of the objective lens. For PC media, the reflected signal has similar polarization dependence, but this dependence is weak. © 2001 Optical Society of America.
• Mansuripur, M. (2001). Gaussian beam optics. Optics and Photonics News, 12(1), 44-47.
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  Abstract: A study is performed on Gaussian beam optics. Gaussian beams are used to study diffraction in the near-field and the far-field, examine beam divergence upon propagation, investigate diffraction-limited focusing through a lens and observe the Gouy phase-shift. The effect of lens on Gaussian beam is also discussed.
• Mansuripur, M. (2001). Launching light into a fiber. Optics and Photonics News, 12(8), 56-59.
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  Abstract: A study was performed on launching light into a single-mode silica glass fiber. The radial gradient-index (GRIN) lens designed to focus a collimated beam of light into the fiber attached to its rear facet was discussed. The method of computing the light amplitude distribution at the focal plane of GRIN lens was presented.
• Mansuripur, M., Xun, X., Peng, C., Saito, K., & Mansuripur, M. -. (2001). Scattering measurements on optical disks and their relation to media noise. Applied optics, 40(26).
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  We have conducted measurements of scattered light from bare polycarbonate and glass substrates and from complete optical disks using a He-Ne laser beam in different polarization states and at different angles of incidence. The results are compared with the measured media noise obtained from the same disks on a dynamic tester. Both the scattered light and the media noise originate from the jaggedness and other imperfections of the groove structure, the roughness of the substrate's surface, and the inhomogeneities of the bulk of the substrate. Although some sources of media noise manifest themselves in the scattered light distribution, others cannot be easily detected by this type of measurement.
• Peng, C., Liang, R., Erwin, J. K., Bletscher, W., Nagata, K., & Mansuripur, M. (2001). Determination of optical constants of thin films and multilayer stacks by use of concurrent reflectance, transmittance, and ellipsometric measurements. Applied Optics, 40(28), 5088-5099.
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  PMID: 18364789;Abstract: Using measurements of reflectance, transmittance, and the ellipsometric parameter Δ, we have determined the thickness, refractive index, and the absorption coefficient of various thin films and thin-film stacks. (Δ, the relative phase between the p- and s-polarized components, is measured for both reflected and transmitted light.) These optical measurements are performed with a specially designed system at the fixed wavelength of λ. = 633 nm over the 10°-75° range of angles of incidence. The examined samples, prepared by means of sputtering on fused-silica substrates, consist of monolayers and trilayers of various materials of differing thickness and optical constants. These samples, which are representative of the media of rewritable phase-change optical disks, include a dielectric mixture of ZnS and SiO2, an amorphous film of the Ge2Sb2.3Te3 alloy, and an aluminum chromium alloy film. To avoid complications arising from reflection and transmission losses at the air-substrate interface, the samples are immersed in an index-matching fluid that eliminates the contributions of the substrate to reflected and transmitted light. A computer program estimates the unknown parameters of the film(s) by matching the experimental data to theoretically calculated values. Although our system can be used for measurements over a broad range of wavelengths, we describe only the results obtained at λ = 633 nm. © 2001 Optical Society of America.
• Peng, C., Mansuripur, M., Ikenishi, M., & Miura, M. (2001). Substrate noise in optical data-storage systems. Applied Optics, 40(20), 3379-3386.
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  PMID: 18360363;Abstract: Noise in optical disk readout has been examined for different polarizations of the incident beam. The disks studied are bare grooved glass substrates, having different groove shapes or differing jaggedness in the sidewalk. We perform measurements for the electric field of the incident laser beam parallel to the track and perpendicular to the track using both differential magneto-optical and conventional phase-change readout schemes. The incident beam of light is focused on the grooved surface of the (bare) substrate either through the substrate or directly from the air. Experiments reveal that the noise level is dependent on the state of polarization, the nature of the track (i.e., land or groove), and the medium of incidence. Surface roughness and sidewall jaggedness are two dominant contributors to the media noise in these substrates. © 2001 Optical Society of America.
• Xun, X., Erwin, J. K., Bletscher, W., Choi, J., Kallenbach, S., & Mansuripur, M. (2001). Crystallization studies on phase-change optical recording media by use of a two-dimensional periodic mark array. Applied Optics, 40(35), 6535-6547.
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  PMID: 18364961;Abstract: We present the results of crystallization studies in thin-film samples of amorphous and crystalline GexSbyTez. The experiments, conducted at moderately elevated temperatures, are based on measurements of the first-order diffraction efficiency from a two-dimensional periodic array of recorded marks. When the samples are slowly heated above room temperature, changes in the efficiencies of various diffracted orders give information about the on-going crystallization process within the sample. Two different compositions of the GeSbTe alloy are used in these experiments. Measurements on Ge2Sb2.3Te5 films show crystallization dominated by nucleation. For the Sb-rich eutectic composition Ge-(SbTe), crystallization is found to be dominated by growth from crystalline boundaries. We also show that crystalline marks written by relatively high-power laser pulses are different in their optical properties from the regions crystallized by slow heating of the sample to moderate temperatures. © 2001 Optical Society of America.
• Xun, X., Peng, C., Saito, K., & Mansuripur, M. (2001). Scattering measurements on optical disks and their relation to media noise. Applied Optics, 40(26), 4728-4737.
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  PMID: 18360515;Abstract: We have conducted measurements of scattered light from bare polycarbonate and glass substrates and from complete optical disks using a He-Ne laser beam in different polarization states and at different angles of incidence. The results are compared with the measured media noise obtained from the same disks on a dynamic tester. Both the scattered light and the media noise originate from the jaggedness and other imperfections of the groove structure, the roughness of the substrate's surface, and the inhomogeneities of the bulk of the substrate. Although some sources of media noise manifest themselves in the scattered light distribution, others cannot be easily detected by this type of measurement. © 2001 Optical Society of America.
• Carriere, J., Narayan, R., Yeh, W., Peng, C., Khulbe, P., Lifeng, L. i., Anderson, R., Choi, J., & Mansuripur, M. (2000). 2 Principles of optical disk data storage. Progress in Optics, 41(C), 97-179.
• Khulbe, P. K., Xun, X., & Mansuripur, M. (2000). Crystallization and amorphization studies of a Ge₂Sb_2.3Te₅ thin-film sample under pulsed laser irradiation. Applied Optics, 39(14), 2359-2366.
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  PMID: 18345146;Abstract: We present the results of crystallization and amorphization studies on a thin-film sample of Ge2Sb2.3Te5, encapsulated in a quadrilayer stack as in the media of phase-change optical disk data storage. The study was conducted on a two-laser static tester in which one laser, operating in pulsed mode, writes either amorphous marks on a crystalline film or crystalline marks on an amorphous film. The second laser, operating at low power in the cw mode, simultaneously monitors the progress of mark formation in terms of the variations of reflectivity both during the write pulse and in the subsequent cooling period. In addition to investigating some of the expected features associated with crystallization and amorphization, we noted certain curious phenomena during the mark-formation process. For example, at low-power pulsed illumination, which is insufficient to trigger the phase transition, there is a slight change in the reflectivity of the sample. This is believed to be caused by a reversible change in the complex refractive index of the Ge2Sb2.3Te5 film in the course of heating above the ambient temperature. We also observed that the mark-formation process may continue for as long as 1 μs beyond the end of the write laser pulse. This effect is especially pronounced during amorphous mark formation under high-power, long-pulse illumination. © 2000 Optical Society of America.
• Liang, R., Erwin, J. K., & Mansuripur, M. (2000). Measurement of the relative optical phase between amorphous and crystalline regions of the phase-change media of optical recording. Applied Optics, 39(13), 2167-2173.
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  PMID: 18345122;Abstract: We describe a method of measuring the relative optical phase on reflection between amorphous and crystalline regions of the phase-change media of optical data storage. With a red He-Ne laser (wavelength, 632.8 nm) the relative phases on two quadrilayer optical disk stacks were measured and found to be ∼40°. The results are in good agreement with the calculated values based on the known layer thicknesses and refractive indices of the stacks. For calibration purposes the height of a known step on an otherwise flat silicon substrate was measured with the same apparatus. The proposed method is fairly simple to set up, can measure both front-surface and through-substrate types of optical disk, and can be used with any laser that has long coherence length. © 2000 Optical Society of America.
• Liang, R., Erwin, J. K., & Mansuripur, M. (2000). Variation on Zernike's phase-contrast microscope. Applied Optics, 39(13), 2152-2158.
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  PMID: 18345120;Abstract: We describe the design, construction, and testing of a variant of Zernike's phase-contrast microscope. The sample is illuminated with a white-light source through an annular aperture, which is projected onto the entrance pupil of the objective lens. In the return path the light diffracted by the sample and appearing in the interior of the objective's aperture (i.e., the test beam) is separated from the light returning in the annular region near the rim of the objective (i.e., the reference beam). The separated beams are relatively phase shifted and then combined to create an interferogram of the sample's surface on a CCD camera. It is fairly straightforward to use this system as a conventional bright-field or dark-field microscope, but its most interesting application is as a Zernike phase-contrast microscope with adjustable amplitude ratio and phase shift between test and reference beams. The ability to continuously adjust the phase of the reference beam also enables quantitative measurement of the phase imparted by the sample to the incident beam. © 2000 Optical Society of America.
• Mansuripur, M. (2000). Bracewell's interferometric telescope. Optics and Photonics News, 11(3), 41-44.
• Mansuripur, M. (2000). Ellipsometry. Optics and Photonics News, 11(4), 52-56.
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  Abstract: A report on the various goals of ellipsometry was presented. Ellipsometry determined the optical and structural constants of thin films and flat surfaces based on the measurements of the ellipse of polarization in reflected or transmitted light. The results of ellipsometric measurements were fed to a computer program that searches the space of unknown parameters.
• Mansuripur, M. (2000). Engineering: Fourier optics, part 2. Optics and Photonics News, 11(6), 44-48.
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  Abstract: An analysis of the Fourier transforming property of a lens, Airy pattern, and Abbe's theory of image formation is presented. In Abbe's theory of image formation, the higher-NA lens, capturing more of the high-frequency Fourier components of the object, yields a superior image. Both lenses, however, fail to reproduce the very fine features of the object.
• Mansuripur, M. (2000). Fourier optics, part 1. Optics and Photonics News, 11(5), 53-57.
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  Abstract: A brief discussion about Fourier optics was presented. It was shown that how decomposition into, and subsequent superposition of plane waves could lead to the near-field (Fresnel) and far-field (Fraunhofer) formulas and eludicate the Fourier transforming properties of a lens. Several numerical examples demonstrating the usefulness of the formulas derived were also presented.
• Mansuripur, M. (2000). Partial polarization, stokes parameters, and the poincaré sphere. Optics and Photonics News, 11(1), 39-43.
• Mansuripur, M. (2000). Rewritable optical disk technologies. Proceedings of SPIE - The International Society for Optical Engineering, 4109, 162-176.
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  Abstract: The present state of technologies for rewritable optical data storage is reviewed. The potentials and pitfalls of the existing technologies are described. Rewritable optical data storage is based on magneto-optical (MO) and phase-change (PC) media technologies. Both the technologies use a focused laser beam to raise the temperature of the medium beyond a certain critical temperature for writing, erasure, and overwriting of data. The storage density of the media, achievable data rates during recording and readout, longevity, reliability, and cost of finished products are some of the factors that characterize the performance of these data storage systems.
• Mansuripur, M. (2000). The magneto-optical Kerr effect. Optics and Photonics News, 11(10), 34-39.
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  Abstract: The magneto-optical Kerr effects are discussed. The Kerr effect can be analyzed with the direction of magnetization of the sample arbitrarily oriented relative to the plane of incidence of the light beam. The magneto-optical effects are best described in terms of the dielectric tensor of the medium in which the interaction between the light and the applied magnetic field takes place.
• Mansuripur, M., & Liang, R. (2000). Projection photolithography. Optics and Photonics News, 11(2), 36-40.
• Mansuripur, M., Wright, E. M., Khulbe, P. K., & Mansuripur, M. -. (2000). Dynamic theory of crystallization in Ge2Sb2.3Te5 phase-change optical recording media. Applied optics, 39(35).
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  We develop a theory of the crystallization dynamics of Ge(2)Sb(2.3)Te(5) thin films that shows good qualitative agreement with experimental reflectivity results from a two-laser static tester. The theory is adapted from the nucleation theory of liquid droplets from supersaturated vapor and elucidates the physics underlying the amorphous-to-crystalline phase transformation under short-pulse excitation. In particular, the theory provides a physical picture in which crystalline islands, or basic embryos, are thermally activated in the amorphous material and subsequently grow as stable nuclei are formed.
• Mansuripur, M., Xun, X., Peng, C., & Mansuripur, M. -. (2000). Estimation of thermal conductivity of magneto-optic media. Applied optics, 39(24).
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  We describe a method to estimate the thermal conductivity of the substrate, the dielectric layer, and the magneto-optic (MO) layer of MO recording media. The method relies on the disappearance of the polar Kerr rotation above the Curie temperature of the MO layer. We obtain the thermal conductivities by taking into account the differences in the heat diffusion behavior under different sized focused spots. The results are reliable to better than 5% accuracy.
• Mansuripur, M., Yeh, W. H., & Mansuripur, M. -. (2000). Evanescent coupling in magneto-optical and phase-change disk systems based on the solid immersion lens. Applied optics, 39(2).
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  Results of numerical computations pertaining to evanescent wave coupling for near-field magneto-optical and phase-change disks based on the concept of the solid immersion lens are presented. We investigated the relation between the coupling efficiency and the width of the air gap in terms of the throughput of the recording process and the resolution of the readout signal. The simulations show a drastic decrease with a widening air gap of the coupling efficiency by means of evanescent waves into the recording medium. In magneto-optical readout, loss of the signal may be attributed to the reduction of magneto-optical interaction, the rise of reflectance, and the variation of the relative phase between the two components of polarization. In the phase-change readout the reduced reflectivity contrast between crystalline and amorphous marks is the cause of signal reduction.
• Mansuripur, M., Yeh, W. H., Li, L., & Mansuripur, M. -. (2000). Computation of effective groove depth in an optical disk with vector diffraction theory. Applied optics, 39(2).
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  Results of vector diffraction simulations pertaining to the effective groove depth for various disks with different groove parameters, different coatings, and different incident polarizations are presented. The effective depth deviates from the physical depth if the track pitch approaches the wavelength of the light source. Moreover, the difference of the effective depth for the two polarization states is demonstrated. The effective depth is usually shallower than the physical depth, especially for deeper grooves. The ray-bending mechanism associated with the objective lens and the different response to s- and p-polarized light on reflection from the disk surface impact the effective depth for objective lenses with different numerical apertures.
• Peng, C., & Mansuripur, M. (2000). Measurement of the thermal conductivity of erasable phase-change optical recording media. Applied Optics, 39(14), 2347-2352.
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  PMID: 18345144;Abstract: We describe a method to estimate the thermal conductivity of the substrate, the dielectric layer, the phase-change (PC) layer, and the reflective layer of PC optical recording media. The method relies on the amorphous-to-crystalline phase transition that occurs in the PC layer and takes advantage of the difference in the thermal diffusion behavior under different-sized focused spots. All the results obtained here are reliable with better than ±5% accuracy, which is within the margin of our experimental error. © 2000 Optical Society of America.
• Peng, C., & Mansuripur, M. (2000). Thermal cross-track cross talk in phase-change optical disk data storage. Journal of Applied Physics, 88(3), 1214-1220.
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  Abstract: We have investigated the temperature distribution in land/groove phase-change optical disks. The incident beam is linearly polarized either parallel to track (E∥ polarization) or tangential to track (E⊥ polarization). Calculations have shown that temperature profiles in the medium are dependent on the wavelength of light, the state of polarization, the geometry of the grooved structure, and the multilayer stack. The temperature profiles are quite different between the land track and the groove track. Thermal cross-track cross talk from a land track to its neighboring groove tracks is higher than that from a groove track to its neighboring land tracks. The interaction between the E⊥ electric field and the grooved structure is mainly responsible for thermal cross-track cross talk. © 2000 American Institute of Physics.
• Saito, K., Miyagawa, N., & Mansuripur, M. (2000). Optical disk noise analysis using rigorous vector diffraction calculations. Proceedings of SPIE - The International Society for Optical Engineering, 4090, 74-81.
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  Abstract: The contributions to noises in optical disk readout caused by the surface roughness on the disk are calculated using a full vector diffraction theory. The sources of noise are assumed to be small periodic bumps existing on land or groove, as well as periodic jaggedness on the groove walls. Under these conditions, the polarization dependence of noise, the difference of noise when the bumps are on land or groove, and the depolarization noise in magneto-optical readout are calculated.
• Tesar, J., Liang, R., & Mansuripur, M. (2000). Optical modeling combining geometrical ray tracing and physical-optics software. Optical Engineering, 39(7), 1845-1849.
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  Abstract: A theory on the construction of a diffraction-limited transmission sphere for interferometry in a geometrical ray-tracing program, followed by an analysis of its performance in physical-optics program is presented. The performance of the design reveals a high theoretical performance in terms of MTF and spot size. The transmission sphere designs were modeled in ZEMAX with DIFFRACT.
• Xun, X., Peng, C., & Mansuripur, M. (2000). Estimation of thermal conductivity of magneto-optic media. Applied Optics, 39(24), 4355-4360.
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  PMID: 18350022;Abstract: We describe a method to estimate the thermal conductivity of the substrate, the dielectric layer, and the magneto-optic (MO) layer of MO recording media. The method relies on the disappearance of the polar Kerr rotation above the Curie temperature of the MO layer. We obtain the thermal conductivities by taking into account the differences in the heat diffusion behavior under different sized focused spots. The results are reliable to better than 5% accuracy. © 2000 Optical Society of America.
• Yeh, W., & Mansuripur, M. (2000). Evanescent coupling in magneto-optical and phase-change disk systems based on the solid immersion lens. Applied Optics, 39(2), 302-315.
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  PMID: 18337898;Abstract: Results of numerical computations pertaining to evanescent wave coupling for near-field magneto-optical and phase-change disks based on the concept of the solid immersion lens are presented. We investigated the relation between the coupling efficiency and the width of the air gap in terms of the throughput of the recording process and the resolution of the readout signal. The simulations show a drastic decrease with a widening air gap of the coupling efficiency by means of evanescent waves into the recording medium. In magneto-optical readout, loss of the signal may be attributed to the reduction of magneto-optical interaction, the rise of reflectance, and the variation of the relative phase between the two components of polarization. In the phase-change readout the reduced reflectivity contrast between crystalline and amorphous marks is the cause of signal reduction. © 2000 Optical Society of America.
• Yeh, W., Lifeng, L. i., & Mansuripur, M. (2000). Computation of effective groove depth in an optical disk with vector diffraction theory. Applied Optics, 39(2), 316-323.
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  PMID: 18337899;Abstract: Results of vector diffraction simulations pertaining to the effective groove depth for various disks with different groove parameters, different coatings, and different incident polarizations are presented. The effective depth deviates from the physical depth if the track pitch approaches the wavelength of the light source. Moreover, the difference of the effective depth for the two polarization states is demonstrated. The effective depth is usually shallower than the physical depth, especially for deeper grooves. The ray-bending mechanism associated with the objective lens and the different response to s- and p-polarized light on reflection from the disk surface impact the effective depth for objective lenses with different numerical apertures. © 2000 Optical Society of America.
• Khulbe, P. K., Xun, X., & Mansuripur, M. (1999). Crystallization and amorphization studies on a Ge₂Sb₂Te₅ thin film sample using a two-laser static tester. Proceedings of SPIE - The International Society for Optical Engineering, 3864, 211-213.
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  Abstract: The results obtained in a novel, two-laser static tester are described, which allows real time monitoring of the crystallization/amorphization processes both during the laser pulse and in the cooling period following the pulse. The two-laser static tester is based on a commercial white light microscope. Crystallization/amorphization studies were conducted for the thermal characterization of phase change media on a set of five quadrilayer samples. The samples have varying thicknesses of GeSbTe and dielectric layers.
• Mansuripur, M. (1999). Nomarski's Differential Interference Contrast Microscope. Optics and Photonics News, 10(9), 34-37.
• Mansuripur, M. (1999). The Faraday effect. Optics and Photonics News, 10(11), 32-36.
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  Abstract: In this issue of Optics and Photonics News, the Engineering column has been expanded to highlight one of the major technical achievements of Michael Faraday, a founding father of the field of electromagnetics.
• Mansuripur, M. (1999). The Shack-Hartmann wavefront sensor. Optics and Photonics News, 10(4), 48-51.
• Mansuripur, M. (1999). The van Cittert-Zemike theorem. Optics and Photonics News, 10(6), 38-42.
• Mansuripur, M. (1999). The van Leeuwenhoek microscope. Optics and Photonics News, 10(10), 39-42.
• Mansuripur, M., Erwin, J. K., Bletscher, W., Khulbe, P., Sadeghi, K., Xun, X., Gupta, A., & Mendes, S. B. (1999). Static tester for characterization of phase-change, dye-polymer, and magneto-optical media for optical data storage. Applied Optics, 38(34), 7095-7104.
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  PMID: 18324256;Abstract: We have designed and built a static tester around a commercially available polarized light microscope. This device employs two semiconductor laser diodes (at 643- and 680-nm wavelengths) for the purpose of recording small marks on various media for optical data storage and for the simultaneous monitoring of the recording process. We use one of the lasers in the single-pulse mode to write a mark on the sample and operate the other laser in the cw mode to monitor the recording process. The two laser beams are brought to coincident focus on the sample through the objective lens of the microscope. The reflected beams are sent through a polarizing beam splitter and thus divided into two branches, depending on whether they are p or s polarized. In each branch the beam is further divided into two according to the wavelength. The four beams thus produced are sent to four high-speed photodetectors, and the resulting signals are used to monitor the reflectance as well as the polarization state of the beam on reflection from the sample. We provide a comprehensive description of the tester's design and operating principles. We also report preliminary results of measurements of phase-change, dye-polymer, and magneto-optical samples, which are currently of interest in the areas of writable and rewritable optical data storage. © 1999 Optical Society of America.
• Mansuripur, M., Lifeng, L. i., & Yeh, W. (1999). Diffraction gratings, part 1. Optics and Photonics News, 10(7), 42-46.
• Mansuripur, M., Peng, C., & Mansuripur, M. -. (1999). Evaluation of partial-response maximum-likelihood detection for phase-change optical data storage. Applied optics, 38(20).
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  We describe the application of partial-response (PR) maximum-likelihood (ML) detection in rewritable phase-change optical data storage. The input to this detector, which is simulated in software, is the actual signal (without any equalization), reproduced from reading of the recorded sequence on an optical disk. The detection algorithm involves the extraction of the impulse response from the readout signal, PR equalization, the adjustment of gain and recovery of clock, ML sequence estimation with the Viterbi algorithm, and analysis of PRML performance. With a laser wavelength of 0.69 microm and an objective lens with a numerical aperture of 0.6, three linear densities are examined: 0.35 and 0.31 microm/bit without modulation code and 0.2 microm/bit with the (1, 7) modulation code. The equalized signal exhibits good eye patterns, especially at the densities of 0.35 and 0.31 microm/bit. Analyses of noise and bit-error rate indicate that jitter, rather than noise, is the main obstacle to realizing ultrahigh density in phase-change media with PRML detection. We also briefly discuss the problem of the inherent nonlinear effect in phase-change readout.
• Mansuripur, M., Sasián, J. M., & Mansuripur, M. -. (1999). Design approaches with a lenslet array and a single, high-numerical-aperture annular-field objective lens for optical data storage systems that incorporate large numbers of parallel read-write-erase channels. Applied optics, 38(7).
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  To achieve very high data rates (>10(9) bits/s) in optical data storage systems it is necessary to employ a large number of laser beams for parallel read-write-erase operations. Bringing all these beams to diffraction-limited focus with a high-numerical-aperture objective lens (while maintaining focus and tracking) requires techniques that are fundamentally different from those that are currently practiced in the field of optical data storage. We present two possible solutions to the problem of designing an objective lens for such systems, one involving an array of high-quality lenslets and the other based on a single, high-numerical-aperture annular-field-of-view conventional lens. Both approaches have advantages and disadvantages, on which we elaborate in the course of our discussions.
• Mansuripur, M., Yeh, W. H., Carriere, J., & Mansuripur, M. -. (1999). Polarization microscopy of magnetic domains for magneto-optical disks. Applied optics, 38(17).
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  Polarization microscopes are widely used to image the magnetic domains of a magneto-optical disk and to characterize the birefringence of the disk substrate. For high-resolution imaging, unfortunately, the coupling of the polarization rotation from the Kerr signal, the effect of Fresnel's reflection coefficients, and the substrate birefringence severely deteriorate the image contrast obtained from conventional observations. Here we present the technique of differential polarization microscopy, which replaces the analyzer with a Wollaston prism, for providing better image contrast. Images of a magnetic pattern obtained with both conventional and differential methods are observed for objective lenses that have different numerical apertures and magneto-optical disks with and without a birefringent substrate. The computer simulations and experimental results show that the use of this differential method improves the image contrast and provides excellent tolerance for defects of the optical system.
• Peng, C., & Mansuripur, M. (1999). Evaluation of partial-response maximum-likelihood detection for phase-change optical data storage. Applied Optics, 38(20), 4394-4405.
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  PMID: 18323926;Abstract: A software detector has been developed to simulate the process of partial-response maximum-likelihood (PRML) detection and to provide great flexibility in the study of the application of PRML to optical data storage. Using this tool, the performance of three linear densities were examined: 0.35 μm/bit without modulation coding, 0.31 μm/bit without modulation coding, and 0.3 μm/bit with the (1, 7) code. The equalized signals exhibit good eye patterns at densities of both 0.35 and 0.31 μm/bit.
• Peng, C., & Mansuripur, M. (1999). Noise and coupling in magnetic super-resolution media for magneto-optical readout. Journal of Applied Physics, 85(9), 6323-6330.
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  Abstract: The Kerr hysteresis loop, the transient thermal response of the Kerr signal, the random magnetization orientation and the effect of magnetic coupling on the noise density and carrier level were examined for exchange- and magnetostatically-coupled central aperture detection-magnetic super-resolution disks.
• Peng, C., & Mansuripur, M. (1999). Studies of the crystallization process in thin films of GeSbTe. Proceedings of SPIE - The International Society for Optical Engineering, 3864, 203-205.
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  Abstract: Some preliminary experimental results on the investigation for the relative significance of photo-induced and thermal effects in phase change (PC) rewritable optical recording are reported. The effects of photoexcitations on the crystallization of the amorphous Ge2Sb2.3Te5 film does not manifest itself in the static experiments. The dynamic experiment, it is not clear if the photoexcitations have a significant effect on crystallization.
• Wolfring, B., Weber, T., Mueller-Wirts, T., & Mansuripur, M. (1999). VERSATEST-I, a versatile polychromatic dynamic testbed for optical disks. Proceedings of SPIE - The International Society for Optical Engineering, 3806, 2-10.
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  Abstract: A polychromatic versatile dynamic testbed for the evaluation of optical disks is presented. The system can be used for all wavelengths from 400 to 690(780) nm, allowing any laser source in this range - especially the new blue laser diodes - to be utilized for read-write-erase experiments. In addition, the system allows testing of disk with substrate thicknesses ranging from 0 to 1.7 mm. The polarization of the system can easily be changed from linear to circular at the disk surface, so the use of both magneto-optical (MO) and phase-change disks (PD) is possible, in addition to read-only disks (CD, DVD). A variable leaky polarizing beam splitter has been specially designed for this tester. This device allows to continuously adjust the ratio between the s- and p- polarized components for the reflected beam reaching the detectors, enabling the optimization of the signal-to-noise ratio while adjusting the relative amounts of the two components of polarization at the detectors. The astigmatic method is used for focus control and the push-pull method is used for track control (other focusing and tracking schemes like DPD are under preparation). In a optional setup, the RF data signal and the focus and track servo signals can be derived from the same high speed quad detectors, allowing the use of the full optical power returning of the disk for all these purposes. So the astigmatic FES, the push-pull TES, the differential magneto-optical readout signal and the conventional sum signal for phase-change readout as well as the differential edge-signal for mark-edge detection are obtained. In this paper, we are presenting the basic functions of VERSATEST-I as well as future enhancements for latest optical data storage technology. Additionally typical test results on magneto-optical disks and phase-change disks (DVD-RAM 5.2GB) are reported.
• Yeh, W., & Mansuripur, M. (1999). Evanescent coupling in magneto-optical and phase-change disk systems based on the solid immersion lens (SIL). Proceedings of SPIE - The International Society for Optical Engineering, 3864, 358-360.
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  Abstract: The impact of evanescent coupling on the throughput of the recording process and the resolution of the readout signal in SIL-based systems is presented. The loss of the MO signal due to a wide gap-width may be attributed to the reduction of magneto-optical activity, the rise in reflectance, and the variation of the relative phase between the two components of polarization over the cross-section of the reflected beam. For PC disks, the reduced reflectivity-difference between the crystalline and amorphous states, and the rise in reflectance are responsible for the reduction of readout signal with the increasing gap-width.
• Yeh, W., Carriere, J., & Mansuripur, M. (1999). Polarization microscopy of magnetic domains for magneto-optical disks. Applied Optics, 38(17), 3749-3758.
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  PMID: 18319982;Abstract: The magnetic domains on a magneto-optical (MO) disk were studied using a novel differential polarization microscope. Incorporating a Wollaston prism and a differential-detection scheme, this microscope eliminates the impact of the four-corners problem and enhances the tolerance of the system to nonuniform illumination, thus improving the image quality. Images of a magnetic pattern for objective lenses with different numerical apertures and for MO disks with and without a birefringent substrate were obtained using both conventional and differential polarization microscopes.
• Yeh, W., Lifeng, L. i., & Mansuripur, M. (1999). Computation of the effective depth of grooves in an optical disk using vector diffraction theory. Proceedings of SPIE - The International Society for Optical Engineering, 3864, 329-331.
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  Abstract: Vector diffraction simulations pertaining to the effective depth of the groove for different track pitches and different numerical apertures (NA) of the objective lens were performed. Results indicate that the effective depth of the groove is different for the incident beam with different polarizations, for the objective lenses with different NAs, and for grooves with different periods. To reduce cross-talk between adjacent tracks, the vector diffraction theory is indispensable for understanding the dependence of the effective depth on the physical depth, numerical aperture, and groove period.
• Mansuripur, M. (1998). Abbe's sine condition. Optics and Photonics News, 9(2), 56-60.
• Mansuripur, M. (1998). Current issues in rewritable optical disk data storage. Biennial IEEE International Nonvolatile Memory Technology Conference, 13-.
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  Abstract: The current trend in rewritable optical data storage is toward the use of novel techniques to achieve densities and data rates that are superior to those achievable in hard disk magnetic recording. We will describe the methodology and potential advantages/disadvantages of solid immersion lens (SIL), front-surface recording, magnetic super resolution (MSR), land & groove recording, and partial response maximum likelihood detection (PRML). We will also discuss the differences between magneto-optical and phase-change media.
• Mansuripur, M. (1998). Evanescent coupling, part 2. Optics and Photonics News, 9(10), 35-38.
• Mansuripur, M. (1998). Evanescent coupling: Part 1. Optics and Photonics News, 9(9), 59-62.
• Mansuripur, M. (1998). Holography and holographic interferometry. Optics and Photonics News, 9(3), 41-45.
• Mansuripur, M. (1998). Michelson's stellar interferometer. Optics and Photonics News, 9(1), 40-43.
• Mansuripur, M. (1998). Polarization microscopy. Optics and Photonics News, 9(11), 36-40.
• Mansuripur, M. (1998). Reciprocity in classical linear optics. Optics and Photonics News, 9(7), 53-58.
• Mansuripur, M. (1998). The Ewald-Oseen extinction theorem. Optics and Photonics News, 9(8), 50-55.
• Mansuripur, M., Lifeng, L. i., & Yeh, W. (1998). Scanning optical microscopy, part I. Optics and Photonics News, 9(5), 56-59.
• Mansuripur, M., Lifeng, L. i., & Yeh, W. (1998). Scanning optical microscopy: Part 2. Optics and Photonics News, 9(6), 42-45.
• Peng, C., & Mansuripur, M. (1998). Sources of noise in erasable optical disk data storage. Applied Optics, 37(5), 921-928.
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  PMID: 18268669;Abstract: Noise sources in the readback signal for phase-change and magneto-optical disks at red, green, and blue wavelengths are examined, and a simple model is presented to explain the observed noise spectra. For phase-change disks the media noise, which corresponds to ∼ 0.4% fluctuation in the disk's amplitude reflection coefficient, is the limiting performance factor for the conventional detection scheme. In magneto-optical media the depolarization noise, whose fluctuations are -0.05% of the disk's reflection coefficient, is the major contributor to the media noise in the differential detection scheme. In phase-change optical disks the main sources of noise are the roughness of the groove profiles and the graininess of the polycrystalline recording layer. In nongrooved regions of the disk the media noise measured with green light is found to be nearly the same as that obtained with the red light. In magneto-optical disks the scattering of light from the rough groove profiles, as well as media inhomogeneities, gives rise to depolarization. Measurements on nongrooved regions of a magneto-optical disk indicate that the media noise obtained with the green light is somewhat higher than that obtained with the red light. © 1998 Optical Society of America.
• Peng, C., Mansuripur, M., & Nagata, K. (1998). Edge detection readout signal and cross talk in phase-change optical data storage. Applied Physics Letters, 72(26), 3422-3424.
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  Abstract: Readout signal, noise, and cross-track cross talk were investigated for edge detection in a phase-change optical data storage system. Both theoretical and experimental results indicate that edge detection has a performance superior to the conventional detection of reflectance variations, especially when the amorphous marks are shorter than the size of the focused spot. More than 50 dB of carrier to noise ratio for marks of 0.36 μm in length is obtained using light at a wavelength of 690 nm and an objective lens of 0.6 numerical aperture. Diffraction analysis on the cross talk has shown that, in the scheme of land-groove recording, there is no optimum groove depth which can cancel the cross talk from adjacent tracks. © 1998 American Institute of Physics.
• Peng, C., Yeh, W., & Mansuripur, M. (1998). Measurements and simulations of differential phase-tracking signals in optical disk data storage. Applied Optics, 37(20), 4425-4432.
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  PMID: 18285893;Abstract: The tracking-error signal generated in differential phase detection (DPD) is theoretically analyzed and numerically simulated. Experimental measurements of the DPD signal versus the tracking offset obtained on compact read-only and phase-change disks are also reported. The signal is sensitive to the geometry of the marks, intersymbol interference along the track, and cross-track cross talk. A characteristic parameter is introduced to relate the DPD signal to the reflectivities of the mark and the spacer. For read-only disks such as CD-ROM and DVD-ROM, the magnitude of the DPD signal does not seem to depend on the reflectivity of the disks, nor does it depend on the pit depth. As for the influence of the various aberrations on the DPD signal, coma in the cross-track direction is shown to give rise to significant tracking offset, whereas defocus and spherical aberrations reduce the magnitude of the DPD signal appreciably. © 1998 Optical Society of America.
• Yeh, W., Bletscher, W., & Mansuripur, M. (1998). High resolution optical shaft encoder for motor speed control based on an optical disk pick-up. Review of Scientific Instruments, 69(8), 3068-3071.
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  Abstract: Using a three-beam optical pick-up from a compact disk player and a flexible, shaft-mounted diffraction grating, we obtain information about the rotation speed and angular position of the motor's spindle. This information may be used for feedback to the motor for smooth operation. Due to the small size of the focused spot and the built-in auto-focus mechanism of the optical head, the proposed encoder can achieve submicrometer resolution. With high resolution, reliable operation, and low-cost elements, the proposed method is suitable for rotary and linear motion control where accurate positioning of an object is required. © 1998 American Institute of Physics.
• Yen, W., Lifeng, L. i., & Mansuripur, M. (1998). Vector diffraction and polarization effects in an optical disk system. Applied Optics, 37(29), 6983-6988.
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  PMID: 18301517;Abstract: The track pitch of current optical disks is comparable with the wavelength of the laser source. In this domain of the pitch-to-wavelength ratio, the complex-diffraction amplitudes are different for different incident polarization states, and the validity of the scalar diffraction theory is questionable. Furthermore, the use of multilayer coatings and high-numerical-aperture beams in modern optical disk technology inevitably entails the excitation of surface waves, which can disturb the baseball pattern significantly. To describe the interaction of a focused beam with a grooved multilayer system fully, it is necessary to have a rigorous vector theory. We use a rigorous vector theory to model the diffraction of light at the optical disk. We present the simulation and the experimental results and demonstrate the ability of this approach to predict or model accurately all essential features of beam-disk interaction, including the polarization effects and the excitation of surface waves. © 1998 Optical Society of America.
• Bartlett, C. L., Kay, D., & Mansuripur, M. (1997). Computer simulations of effects of disk tilt and lens tilt on push-pull tracking error signal in an optical disk drive. Applied Optics, 36(32), 8467-8473.
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  PMID: 18264391;Abstract: We quantify the effects of disk tilt and objective lens tilt on the push-pull tracking error signal of an optical disk data storage system. For a grooved disk, such as a recordable compact disk that operates at a laser wavelength of λ, it is found that disk tilt produces a tracking offset of 0.05λ per degree of tilt, whereas objective lens tilt produces an offset of 0.012λ. per degree of tilt. The amplitude of the tracking error signal decreases by 2.5% at the disk tilt angle of 0.3° and by 5% at the objective lens tilt of 0.3°. We achieved these simulations with the computer program DIFFRACT, which performs a combination of diffraction and ray-tracing calculations through the entire optical path, from the light source to the detectors. © 1997 Optical Society of America.
• Bartlett, C., Kay, D., & Mansuripur, M. (1997). Computer simulations of the effects of disk tilt and lens tilt on the push-pull tracking error signal in an optical disk drive. Topical Meeting on Optical Data Storage - Digest of Technical Papers, 85-86.
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  Abstract: The results of computer simulations pertaining to the offset of the point of peak irradiance from track center and the accompanying change of the tracking error signal (TES) amplitude was reported. In an optical disk drive, both disk tilt and objective lens tilt induce tracking difficulties. The effects of disk tilt on tracking servo are more severe than those of the objective lens tilt because the displacement of the focused spot caused by disk tilt is over twice that caused by lens tilt and because the focused spot is more asymmetric in the presence of disk tilt compared to the case of lens tilt.
• Cheng, L., & Mansuripur, M. (1997). Measurement of the thermal coefficients of erasable phase-change media. Topical Meeting on Optical Data Storage - Digest of Technical Papers, 96-97.
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  Abstract: A new method was developed for determining the thermal coefficients of erasable phase change films. The method consists of monitoring the reflectivity variations of a PC sample during the writing process. The system uses a 1.7 μs laser pulse at a fixed power level to create a hot spot under the focused beam, while simultaneously observing the reflectivity variations. The amount of reflected light does not increase initially after the laser has been turned on; there is a knee in each curve that corresponds to the onset of noticeable reflectivity change. Two single layer PC samples were measured using this technique: one was a 35 nm-thick sample and the other was 90 mm thick, both coated on identical glass substrate.
• Cheng, L., Bartlett, C. L., Erwin, J. K., & Mansuripur, M. (1997). Leaky polarizing beam splitter with adjustable leak ratio for operation in the wavelength range of 440-690 nm. Applied Optics, 36(19), 4393-4399.
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  PMID: 18259226;Abstract: We discuss the optomechanical design and fabrication of a novel wideband (440-690-nm), leaky polarizing beam splitter with an adjustable leak ratio. This beam splitter is an important component of a multiwavelength dynamic testbed that we have constructed for testing optical disks. The multilayer thin-film structure of the beam splitter is essentially a stacked pair of narrow-band dielectric reflectors that have been fine tuned for optimal performance. The characteristics of the fabricated device are in good agreement with our theoretical calculations. © 1997 Optical Society of America.
• Hsieh, Y., & Mansuripur, M. (1997). Image contrast in polarization microscopy of magneto-optical disk data-storage media through birefringent plastic substrates. Applied Optics, 36(20), 4839-4852.
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  PMID: 18259287;Abstract: Using polarized-light microscopy, we have investigated the magnetic domains of perpendicularly magnetized media under several different conditions, including direct observation of the thin-film magnetic layer and observations through the glass or plastic substrates on which the magnetic film was deposited. The results show that the image contrast is reduced with an increasing numerical aperture of the objective lens. They also indicate that the polarization rotation caused by differences between the reflectivity-transmissivity of the p and s components of polarization deteriorate the magnetic image contrast. Furthermore, by comparing the image quality using the same objective lens on samples having different substrates, we found that the images obtained through plastic substrates are worse than those obtained through glass substrates. Birefringence of the plastic substrate is shown to be responsible for the additional degradation of the image contrast. © 1997 Optical Society of America.
• Hsieh, Y., & Mansuripur, M. (1997). Image contrast in polarization microscopy of magneto-optical media through plastic substrates. Topical Meeting on Optical Data Storage - Digest of Technical Papers, 70-71.
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  Abstract: The magnetic domains of a perpendicularly magnetized media under different conditions that include the observations of the thin-film magnetic layer and observations through the glass or plastic substrate on which the magnetic film was deposited were observed using polarized light microscopy. The image contrast was reduced with increasing numerical aperture (NA) of the objective lens. The magnetic image contrast deteriorated when the polarization is caused by the differences between reflectivity/transmisivity of the p- and s-components of the polarization. Image quality obtained through the glass substrate is better than the image obtained in the plastic substrate due to the presence of vertical birefringence in plastic substrates.
• Hsieh, Y., Gadetsky, S., Suzuki, T., & Mansuripur, M. (1997). Oblique sputtering of amorphous TbFeCo thin films on glass substrates and the effect of deposition angle on perpendicular magnetic anisotropy. Journal of Applied Physics, 81(8), 3555-3560.
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  Abstract: We measured the magnetic hysteresis loops for several obliquely deposited amorphous TbFeCo films. The experimental results snow that the direction of the average magnetic anisotropy (i.e., the easy axis of magnetization) is no longer along the surface normal. With the help of computer simulations, we have quantified the effects of oblique deposition in terms of the deviations of local anisotropy directions from the surface normal. We also found that, with the increasing of the deposition angle, the compensation point shifts toward the Fe-rich side and the films become thinner. © 1997 American Institute of Physics.
• Hsieh, Y., Mansuripur, M., Volkmer, J., & Brewen, A. (1997). Measurement of the thermal coefficients of nonreversible phase-change optical recording films. Applied Optics, 36(4), 866-872.
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  PMID: 18250751;Abstract: We have developed a procedure to obtain the critical temperature for the amorphous-to-crystalline phase transition as well as the thermal conductivity and the specific heat of the phase-change media of optical recording. The procedure involves estimating the thermal conductivity from the data obtained by measuring the threshold cw laser power required for inducing phase transition. Then, from the data obtained in short-pulse measurements, we estimate the specific heat. In principle this method can yield the thermal parameters of any number of layers, so long as one of the layers is made of a phase-change material having a well-defined transition temperature. © 1997 Optical Society of America.
• Mansuripur, M. (1997). Coherent and incoherent imaging. Optics and Photonics News, 8(10), 40-44.
• Mansuripur, M. (1997). External conical refraction. Optics and Photonics News, 8(8), 50-52.
• Mansuripur, M. (1997). Fabry-Perot étalons in polarized light. Optics and Photonics News, 8(3), 39-44.
• Mansuripur, M. (1997). Some guirks of total internal retlection. Optics and Photonics News, 8(2), 36-39.
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  Abstract: In this column, Masud Mansuripur describes, in simple and direct form, the details of a well known optical phenomenon. The purpose is to provide some of the subtle characteristics of the physics behind the effect, without a lot of extraneous mathematics. This article, and similar ones to be published in the future, will help those working in applied optics to gain a better appreciation of the details and physics behind various well known phenomena.
• Mansuripur, M. (1997). The method of fox and li. Optics and Photonics News, 8(9), 38-41.
• Mansuripur, M. (1997). Zernike's method of phase contrast. Optics and Photonics News, 8(11), 40-43.
• Mansuripur, M., & Sincerbox, G. (1997). Principles and techniques of optical data storage. Proceedings of the IEEE, 85(11), 1780-1796.
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  Abstract: We review the field of optical data storage and describe the various technologies that either are in use today or are likely to play a role in the near future. Our emphasis will be on optical-disk and holographic optical storage. © 1997 IEEE.
• Mansuripur, M., Erwin, J., Bletscher, W., Kim, S. G., Lee, S. K., Peng, C., Gerber, R. E., Bates, K., Bartlett, C., Goodman, T. D., Cheng, L., Chung, C. S., & Kim, T. (1997). Versatile polychromatic dynamic testbed for testing of optical disks. Topical Meeting on Optical Data Storage - Digest of Technical Papers, 94-95.
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  Abstract: A dynamic testbed has been designed and constructed for the evaluation of optical disks. Within the wavelength range of 440 nm to 690 nm, the system is achromatic, allowing any light source in this range to be utilized for read/write/erase experiments. The system also accepts disks with substrate thickness ranging from 0 to 1.7 mm. The testbed handles polarization such that with a turn of a knob, one can generate either linearly-polarized or circularly-polarized light at the disk surface. Focus error detection is based on the astigmatic method, and the primary track error detection scheme is the push pull method. The detection channel consists of two high-speed quad detectors mounted on the two arms of a differential detection module.
• Mansuripur, M., Peng, C., Erwin, J. K., Bletscher, W., Kim, S. G., Lee, S. K., Gerber, R. E., Bartlett, C., Goodman, T. D., Cheng, L., Chung, C. S., Kim, T., & Bates, K. (1997). Versatile polychromatic dynamic testbed for optical disks. Applied Optics, 36(35), 9296-9303.
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  PMID: 18264488;Abstract: A dynamic testbed for the evaluation of optical disks has been designed and constructed. The system is achromatic within the wavelength range 440-690 nm, allowing any light source in this range to be utilized for read-write-erase experiments. In addition, the system accepts disks with substrate thicknesses ranging from 0 to 1.7 mm. The polarization handling capabilities of the testbed are such that, with the turn of a knob, one can generate either linearly polarized or circularly polarized light at the disk surface. This feature permits the testing of both magneto-optical and phase-change disks, in addition to compact disks and digital versatile disks, without any modifications to the system. A leaky polarizing beam splitter (LPBS) has been specially designed and built for this tester. The LPBS allows continuous adjustment of the ratio between p- and s-polarized components of the reflected beam that reach the detectors. This feature is especially useful for magneto-optical disks, where one can achieve an optimum signal-to-noise ratio by adjusting the relative amounts of the two components of polarization at the detection module. Focus-error detection is based on the astigmatic method, and the primary track-error detection scheme is the push-pull method, although other focusing and tracking schemes may also be implemented. The rf data signal and the focusing and tracking servo signals are all derived from the same detectors, thus allowing the optical power returning from the disk to be used in its entirety for these multiple purposes. The detection channel consists of two high-speed quad detectors mounted on the two arms of a differential detection module. By combining the various outputs of these detectors it is possible to generate the astigmatic focus-error signal, the push-pull track-error signal, the differential magneto-optical readout signal, the conventional sum signal for phase-change disk readout, and the differential edge-signal for mark-edge detection on various types of optical media. © 1997 Optical Society of America.
• Peng, C., & Mansuripur, M. (1997). Edge detection in phase-change optical data storage. Topical Meeting on Optical Data Storage - Digest of Technical Papers, 32-33.
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  Abstract: An edge detection scheme for phase change systems is presented. A single split detector is used to detect the intensity of reflected beam in the far field, and the readout signal, which relies on diffraction from mark boundaries, is the difference signal of the split-detector. The magnitude of the readout signal for edge detection is derived by clarifying the effect of phase on the read signal, and comparing noise levels at the output of readout systems using edge detection and sum detection.
• Peng, C., & Mansuripur, M. (1997). Sources of noise in phase-change disk data storage. Topical Meeting on Optical Data Storage - Digest of Technical Papers, 36-37.
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  Abstract: In optical disk storage, it is essential to control the sources of noise in order to achieve high signal to noise ratio (SNR) and eventually a low byte error rate. Separate various noises for phase change (PC) disks are analyzed in detail. In PC optical data storage, the media noise, which corresponds to about 1% fluctuations of the disk reflection coefficient, is the limiting factor for high SNR if one uses the sum detection technique scheme in the data channel.
• Peng, C., Cheng, L., & Mansuripur, M. (1997). Experimental and theoretical investigations of laser-induced crystallization and amorphization in phase-change optical recording media. Journal of Applied Physics, 82(9), 4183-4191.
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  Abstract: We describe the numerical procedure for calculating three-dimensional profiles of temperature in a multilayer stack illuminated by a laser beam, and model the crystallization and amorphization kinetics for phase-change rewritable media. Experimental methods have been used to determine indirectly the probabilities of nucleation and growth for Ge2Sb2Te5 alloy. Some of the fundamental behaviors of phase-change erasable media, such as the crystallization of as-deposited amorphous phase, amorphization of supercooled liquid, and recrystallization of quenched amorphous phase, have been illustrated based on our three-dimensional temperature calculations and the model kinetics. The calculated transient reflectance behavior of as-deposited Ge2Sb2Te5 amorphous films in a single layer and in a quadrilayer stack, as well as the erasure behavior of Ge2Sb2Te5 alloy in a quadrilayer disk are in good agreement with experimental observations, © 1997 American Institute of Physics.
• Peng, C., Mansuripur, M., Kim, W. M., & Kim, S. G. (1997). Edge detection in phase-change optical data storage. Applied Physics Letters, 71(15), 2088-2090.
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  Abstract: A direct mark edge detection scheme for readout in phase-change optical disk systems is described. The medium for edge detetection must be optimized to have a 90° phase difference between the amorphous mark and the crystalline space. Theoretical analysis and numerical simulation have shown that the readout signal using mark edge detection is as good as that using conventional detection of reflectivity for long marks and superior for short marks. Noise level at the output of differential edge detection is lower than that at the output of conventional detection. We also show experimental results that confirm these predictions. © 1997 American Institute of Physics.
• Yoo, J., Lee, C., Shin, D., Bartlett, C., Cheong, K., Erwin, J. K., & Mansuripur, M. (1997). Investigation of certain diffraction effects in a double-layer optical disk. Proceedings of SPIE - The International Society for Optical Engineering, 3109, 150-158.
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  Abstract: We report certain diffraction effects that are pertinent to the operation of double-layer optical recording media. The diffraction of light from the out-of-focus layer and the resulting distribution on the in-focus layer are studied using computer simulations. The findings are then verified by direct measurements. We also describe a technique for analyzing (by computer simulation) the focus-error signal, FES, in systems that use the astigmatic method in conjunction with the double-layer disk. The results of our computer simulations of the FES are compared with those measured in an actual disk drive; good agreement between computation and measurement is obtained.
• Yoo, J., Lee, C., Shin, D., Bartlett, C., Cheong, K., Erwin, J. K., & Mansuripur, M. (1997). Investigation of certain diffraction effects in an optical disk. Applied Optics, 36(35), 9287-9295.
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  PMID: 18264487;Abstract: We report certain diffraction effects that are pertinent to the operation of double-layer optical recording media. For simulating cross-talk effects for double layers, the diffraction of light from the out-of-focus layer and the resulting distribution on the in-focus layer are studied by use of computer simulations. The findings are then verified qualitatively by direct measurements. We also describe a technique for analyzing (by computer simulation) the focus-error signal (FES), taking into account the cross talk between two layers, in systems that use the astigmatic method in conjunction with the double-layer disk. The results of our computer simulations of the FES give us a 10% cross-talk contribution to the original signal. The results of the FES evaluation are compared with those measured in an actual disk drive; good agreement between computation and measurement is obtained. © 1997 Optical Society of America.
• Yoo, J., Lee, C., Shin, D., Bartlett, C., Cheong, K., Erwin, J., & Mansuripur, M. (1997). Investigation of certain diffraction effects in a double-layer optical disk. Topical Meeting on Optical Data Storage - Digest of Technical Papers, 87-89.
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  Abstract: Computer simulations and experimentations were carried out to study the diffraction of the incident beam from the grooved structure of the first layer unto the second layer of a double layer optical disk. The cross-talk between focus error signal (FES) curve obtained from the two layers of the disk was also examined. Good qualitative agreement has been obtained between simulations and measurement.
• Gadetsky, S., & Mansuripur, M. (1996). Barkhausen jumps during domain wall motion in thin magneto-optical films. Journal of Applied Physics, 79(8 PART 2B), 5667-5669.
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  Abstract: A method with high spatial resolution is developed to study wall motion in thin magnetic films with perpendicular anisotropy. Barkhausen jumps during domain wall motion in amorphous TbFeCo films and polycrystalline Co/Pd multilayer films have been observed. The average distance between strong pinning sites in Co/Pd was found to be around 0.3-0.4 μm. Maximum pinning times as long as several seconds were observed. Magnitudes of major jumps in TbFeCo were around 0.7 μm. © 1996 American Institute of Physics.
• Gadetsky, S., Erwin, J. K., Mansuripur, M., & Suzuki, T. (1996). Magneto-optical recording on patterned substrates (invited). Journal of Applied Physics, 79(8 PART 2B), 5687-5692.
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  Abstract: Patterning of glass or plastic substrates in the form of shallow square patches is a promising method of increasing the storage density for magneto-optical disks. The sidewalls of the patches pin the reverse-magnetized domains that develop in these samples. Confinement of domains within the patch boundaries during thermomagnetic recording has also been demonstrated. We have measured polarization conversion of the incident light on the sidewalls of the patches; a method to reduce the amount of such polarization conversion is proposed in this article. © 1996 American Institute of Physics.
• Gadetsky, S., Syrgabaev, I., Erwin, J. K., Mansuripur, M., Suzuki, T., & Ruane, M. (1996). Measurements of the magneto-optic Kerr effect and the extraordinary Hall effect on grooved glass substrates coated with amorphous TbFeCo. Journal of the Optical Society of America A: Optics and Image Science, and Vision, 13(2), 314-319.
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  Abstract: Kerr loops measured in the 0th, -1st, and -2nd diffraction order beams on deep magneto-optic gratings show constructive and destructive interference of the beams reflected from grooves and lands as a function of effective phase depths and relative widths of grooves and lands. Hall-effect measurements yielded coercivities of grooves, lands, and sidewalls at different angles of the applied field. Sidewall reversals appear clearly in Kerr loops measured in the various diffracted beams, with signal amplitude depending on groove depth and the angle between the sidewall and the diffracted beam. © 1996 Optical Society of America.
• Gerber, R. E., & Mansuripur, M. (1996). Tilt correction in an optical disk system. Applied Optics, 35(35), 7000-7007.
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  PMID: 21151300;Abstract: A servo system for the correction of disk tilt in optical disk data storage is proposed, and its basic concepts are demonstrated by the use of a static system in which the disk does not spin. Because disk tilt produces primarily coma in the beam focused onto the disk, the system uses a variable coma generator to produce an equal and opposite amount of coma as that caused by the tilted disk. The magnitude and direction of disk tilt are detected by the use of the light reflected from the front facet of the disk substrate. © 1996 Optical Society of America.
• Goodman, T. D., & Mansuripur, M. (1996). Optimization of groove depth for cross-talk cancellation in the scheme of land-groove recording in magneto-optic disk systems. Applied Optics, 35(7), 1107-1119.
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  PMID: 21085221;Abstract: In the scheme of land-groove recording in magneto-optic disk data-storage systems, it has been shown that an optimum groove depth exists at which the cross talk from adjacent tracks diminishes. Cross-talk cancellation, however, is very sensitive to various parameters of the system, and, in particular, the presence of substrate birefringence can have devastating effects on system performance. We analyze the origin of the observed effects by using scalar diffraction theory, and we show the reasons behind cross-talk cancellation. We also explain the relation between substrate birefringence and cross talk in simple analytical terms. Extensive computer simulations have been performed to verify and extend the theoretical results of this paper; the results of some of these simulations are also presented. © 1996 Optical Society of America.
• Goodman, T. D., & Mansuripur, M. (1996). Subtle effects of the substrate in optical disk data storage systems. Applied Optics, 35(34), 6747-6753.
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  PMID: 21151258;Abstract: Much attention has been focused on the effects of the disk substrate in optical data storage. In particular, substrate birefringence has been studied extensively because it causes significant problems in magneto-optic systems. We investigate certain subtle effects of the substrate, such as feedback into the laser diode, in compact disk and phase-change systems. Our analysis of the compact disk system led us to discover a new technique for the rapid measurement of the substrate birefringence. We also address the question of how focusing the laser beam through the substrate will affect the depth of focus. © 1996 Optical Society of America.
• Goodman, T. D., Gerber, R. E., & Mansuripur, M. (1996). Temperature dependence of the birefringence of optical-disk substrates. Applied Optics, 35(16), 3031-3038.
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  PMID: 21085455;Abstract: Injection-molded polycarbonate substrates are used predominantly in read-only, write-once, phase-change and magneto-optic disks for data storage. The in-plane and vertical birefringences of these substrates adversely affect the performance of optical data-storage systems. The disks are typically expected to operate in the ambient temperature range of 5-50 °C. We have investigated the behavior of the in-plane and vertical birefringences of a polycarbonate disk substrate in this temperature range using a custom-built ellipsometer. This study reveals that the in-plane birefringence changes dramatically within the investigated range of temperatures, whereas the vertical birefringence remains essentially constant. We suspect that the change in birefringence is due primarily to thermally induced stress in the substrate. © 1996 Optical Society of America.
• Hsieh, Y., Gadetsky, S. N., Mansuripur, M., & Takahashi, M. (1996). A dynamic study of domain formation mechanism during thermomagnetic recording based on micro-Hall effect measurements. Journal of Applied Physics, 79(8 PART 2B), 5700-5702.
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  Abstract: A method for analyzing the dynamics of domain formation during the thermomagnetic recording process has been developed based on the extraordinary Hall effect.1,2 A magnetic domain is written at the center of a cross-shaped magneto-optical sample having an area of 5×5 μm2, and the Hall voltage is monitored during the recording process. As far as domain nucleation is concerned, we find that the temperature gradient around the transition region (i.e., the region whose temperature is between the critical temperature for magnetization reversal and the Curie point) is very important. Under the conditions of high power and short pulse-width laser, a domain can form only during the cooling period. However, it is possible for a domain to form during the heating cycle under a low power, long pulse laser beam. © 1996 American Institute of Physics.
• Mansuripur, M. (1996). Propagation of the laser beam in optical disk data storage systems. Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS, 100-.
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  Abstract: The quality of the beam of a semiconductor laser diode must remain very high throughout the entire optical path. Small amounts of aberration or polarization conversion can destroy the performance of an optical disk drive. Astigmatism of the laser, birefringence of the substrate, tilt of the objective lens (or of the disk), are some of the factors that can seriously degrade the beam quality. In this presentation, some of the theoretical and experimental results that demonstrate the various effects of the optical path on read/write/erase processes of an optical disk data storage system are described.
• Gadetsky, S., Suzuki, T., Erwin, J. K., & Mansuripur, M. (1995). Thermomagnetic recording in amorphous TbFeCo films on patterned substrates. IEEE Transactions on Magnetics, 31(6 pt 1), 3253-3255.
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  Abstract: Magnetization reversal and thermomagnetic recording in amorphous TbFeCo films on patterned glass substrates were studied. Two types of patterns were examined: 1×1 μm2 raised and lowered square patches. Pinning of the domain walls at the side-walls of the patches was observed. Thermomagnetic recording experiments confirm the ability of patterned substrates to confine recorded domains within boundaries defined by the side-walls.
• Hong, F. u., Goodman, T., Sugaya, S., Erwin, J. K., & Mansuripur, M. (1995). Retroreflecting ellipsometer for measuring the birefringence of optical disk substrates. Applied Optics, 34(1), 31-39.
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  Abstract: Presented is a study of a constructed retroreflecting ellipsometer that would measure birefringence of optical disk substrates. Through the single-arm architecture and the hemispherical assembly, this equipment permits the probe beam to go through the substrate in a wide range of polar as well as azimuthal angles. Provided is a solution to the problems caused by index-matching oil and the substrate.
• Hong, F. u., Yan, Z., Lee, S. K., & Mansuripur, M. (1995). Dielectric tensor characterization and evaluation of several magneto-optical recording media. Journal of Applied Physics, 78(6), 4076-4090.
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  Abstract: A dielectric tensor database for magneto-optical (MO) thin film media in high density MO recording has been established. The measurement method used involves a combination of variable angle ellipsometry, reflection-transmission measurements, and polar Kerr effect measurements. The MULTILAYER program is used to analyze the measurements data and search for the best-estimate values of the unknown parameters. This method, which comprises measurements at a wide range of incident angles and at different wavelengths, provides a high degree of accuracy for characterizing the thickness and the dielectric tensor elements of thin film samples. The wavelength dependence of the dielectric tensor is obtained for the following MO materials: (BiDy)3(FeGa)5O12, MnBi, multilayered Co/Pt, TbFeCoTa, and fcc cobalt. The measurement results for the Heusler alloy PtMnSb, which has been available from the literature, is summarized. In the blue-green regime, the relationship among the derived values of figure of merit for these materials is given.
• Hsieh, Y., & Mansuripur, M. (1995). Coercivity of magnetic domain wall motion near the edge of a terrace. Journal of Applied Physics, 78(1), 380-386.
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  Abstract: Domain wall motion near the edges of terraces (e.g., grooves, pits, plateaus, etc.) is studied using analytical techniques based on the minimum energy principle and computer simulations based on the dynamic Landau-Lifshitz-Gilbert equation. One-dimensional lattices of magnetic dipoles with variations either of the easy axis direction (corresponding to a tilt of the anisotropy axis at the edge) or of the nearest-neighbor exchange force (corresponding to a changing film thickness) are considered. We show that the coercivity caused by the terrace edge could be as large as several kilo Oe. © 1995 American Institute of Physics.
• Bernacki, B. E., & Mansuripur, M. (1994). Causes of focus-error feedthrough in optical-disk systems: astigmatic and obscuration methods. Applied Optics, 33(5), 735-743.
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  Abstract: This paper discusses the phenomena of feedthrough which is a result of the interaction of the tracking-error signal (TES) with the focus-error signal (FES) in optical disk systems using push-pull tracking in grooved media. A computer model is used to study the FES and the optical beams phase distribution and intensity along the optical path and describe its mechanism and cause. The astigmatic and obscuration methods are used for the analysis and show that when 45° astigmatism is present the astigmatic yields the largest FES feedthrough. The two causes investigated were the phase and amplitude distribution of the reflected beam at the exit pupil of the objective lens.
• Gadetsky, S., Suzuki, T., Erwin, J. K., & Mansuripur, M. (1994). Effect of grooves on magnetization reversal in amorphous TbFeCo thin films. IEEE Transactions on Magnetics, 30(6 pt 1), 4404-4406.
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  Abstract: We have investigated the effect of grooves milled by argon ions in soda lime glass substrates on the magnetic behavior of amorphous TbFeCo films deposited onto these substrates. The domains are shown to expand along the grooves when the groove depth exceeds 10 nm. The effect originates from the difference in the coercivities of the film on the land and on the groove, as well as from the pinning of domain walls by the side-walls of the grooves.
• Hong, F. u., Sugaya, S., & Mansuripur, M. (1994). Measuring distribution of the ellipsoid of birefringence through the thickness of optical disk substrates. Applied Optics, 33(25), 5994-5998.
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  Abstract: Distribution of birefringence through substrate thickness is measured by a nondestructive method. Ellipsoid of birefringence tilt in r-z plane is a general feature for polycarbonate substrates. A conversion between p and s components of polarization can be caused by this tilt. Probable cause of the tilt is the velocity gradients during injection-molding process.
• Hong, F. u., Sugaya, S., Erwin, J. K., & Mansuripur, M. (1994). Measurement of birefringence for optical recording of disk substrates. Applied Optics, 33(10), 1938-1949.
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  Abstract: Using ellipsometry, a method of birefringence measurement of optical disk substrates is described. The method involves measuring the rotation and ellipticity, and fitting data with the MULTILAYER program. Measurements of a broad range of incident angles with high degree of accuracy were obtained using a glass hemisphere. Birefringence properties of several bare and coated substrates are studied.
• Hong, F. u., Wu, T., & Mansuripur, M. (1994). Direct measurement of subnetwork exchange coupling constant for ferrimagnets. Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 33(5 A), 2541-2543.
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  Abstract: We show that the subnetwork exchange coupling constant λ of ferrimagnetic films is equal to the slope of the plot of the magnetic field H applied in the film plane versus the in-plane magnetization M∥ at compensation temperature Tcomp, i.e. H = λM∥ at Tcomp. This finding enables the direct measurement of λ for ferrimagnetic magneto-optical recording thin films, regardless of the complexity of the two-subnetwork problem. The experimental results are within the range predicted by the mean-field theory.
• Hong, F. u., Yan, Z., & Mansuripur, M. (1994). Measurement of the wavelength dependence of birefringence for optical disk substrates. Applied Optics, 33(31), 7406-7411.
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  Abstract: This paper presents a theoretical and experimental measurement of the effect of wavelength on birefringence in polycarbonate substrates, in the range from 360 to 860 nm, which covers the blue, red and infrared recording range. Results show that as the measurement wavelength increases, the birefringence generally decreases.
• Mansuripur, M., & Hsieh, Y. (1994). Novel method for measuring the vertical birefringence of optical disk substrates. Applied Optics, 33(34), 8112-8114.
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  Abstract: A simple technique of measuring vertical birefringence over the entire surface of an optical disk substrate was presented. The design involves a linearly polarized He-Ne laser and a CCD camera interfaced to a computer. The measurement is basically non-intrusive, easy to set up, and requires only a few seconds to gather the data and plot a map of vertical birefringence over the surface area of the disk. The system present is potentially advantageous as quality-control instrument in substrate manufacturing environments.
• Sugaya, S., & Mansuripur, M. (1994). Effect of titled ellipsoid of birefringence on readout signal in magneto-optical disk data storage. Applied Optics, 33(25), 5999-6008.
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  Abstract: Numerical analysis is performed to study the effects tilted ellipsoid of birefringence on the readout in magneto-optical (MO) data storage systems. Tilt of the ellipsoid and the residual phase shifts within the optical head in various combinations, could improve or degrade the quality of the MO signals to varying degrees.
• Sugaya, S., & Mansuripur, M. (1994). Effects of substrate birefringence on focusing and tracking servo signals in magneto-optical disk data storage. Applied Optics, 33(22), 5073-5079.
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  Abstract: This paper presents an analytical investigation of the interaction of servo signals (for focusing and tracking) and the substrate birefringence for magneto-optical disk storage systems. Results of the computer simulation using the program DIFFRACT show that spherical aberrations and astigmatism of the beam, and enhancements due to the substrate birefringence have various effects on the feedthrough signal. While some combinations have only minimal effects on track crossing, others could force the disk out of focus before they are nulled out.
• Zambuto, J. J., Gerber, R. E., Erwin, K. J., & Mansuripur, M. (1994). Ring-lens focusing and push-pull tracking scheme for optical disk systems. Applied Optics, 33(34), 7987-7994.
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  Abstract: The study presents a comparison of the ring-lens and astigmatic methods of generating focus-error and track-error signals for optical disk drives. It was found out that the ring-lens scheme produces a substantially steeper focus-error signal (FES) curve than the astigmat is tolerant of small errors in detector positioning and alignment.
• Bernacki, B. E., Bates, K., Mansuripur, M., Hansen, D., & Cisneros, D. (1993). Characterization of a novel focusing/tracking technique with increased feedthrough immunity for optical-disk applications: The double-astigmatic method. Applied Optics, 32(29), 5789-5796.
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  PMID: 20856401;Abstract: The astigmatic-focusing/push-pull tracking-error detection method is an elegant and sensitive optical servo technique. Unfortunately the formation of error signals far from either line focus of the astigmat (for relaxing alignment tolerances and broadening the servo's acquisition range) gives rise to undesired diffraction effects in the focus servo channel owing to track crossings of the pregrooved disk by the optical stylus, especially if certain aberrations are present. These undesired effects are given several names: pattern noise, optical servo cross talk, and feedthrough. By combining two astigmatic lenses and their associated detectors, one can configure a differential variant of the astigmatic technique. This double-astigmatic method greatly reduces pattern noise caused by the presence of spurious astigmatism oriented with its line foci at +450 to the disk tracks. In this paper we present numerical modeling and experimental data that demonstrate the effectiveness of this focusing/tracking technique in feedthrough suppression. © 1993 Optical Society of America.
• Bernacki, B. E., Bates, K., Mansuripur, M., Hansen, D., & Cisneros, D. (1993). Characterization of a novel focusing/tracking technique with increased feedthrough immunity for optical-disk applications: the double-astigmatic method. Journal of the Optical Society of America B: Optical Physics, 10(1), 5789-5796.
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  Abstract: A presentation is given of a novel focusing tracking technique with increased feedthrough immunity applied to optical disks. The double-astigmatic method is discussed. A description is given of the system model and of the single-astigmatic method. The double-astigmatic method and plots of intensity of the detector plane for the beam centered on the land when 45 degrees astigmatism is presented are given.
• Bernacki, B. E., Wu, T., & Mansuripur, M. (1993). Assessment of local variations in the coercivity of magneto-optical media. Journal of Applied Physics, 73(10), 6838-6840.
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  Abstract: Locally varying deposition conditions and substrate characteristics of magneto-optic media may alter the domain nucleation, growth, and collapse mechanisms of the film. The use of a static tester and basic image processing equipment permits qualitative observations of anomalous domain nucleation, growth, and collapse phenomena. We present example images for a Co/Pt sample and several TbFeCo films that depict symmetrical domain expansion and collapse, directional preference for domain wall motion, domain collapse from submicroscopic domain remnants, and anomalous domain nucleation and expansion as a function of position on the sample.
• Mansuripur, M., & Bernacki, B. E. (1993). Investigation of substrate birefringence effects on optical-disk performance. Applied Optics, 32(32), 6547-6555.
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  Abstract: Substrates for Magneto-optical disks are produced efficiently and economically by injection molding of polycarbonate plastics. plastics. However, most plastics are birefringent, with different refractive indices in the plane of the disk (lateral birefringence) and perpendicular to the plane of the disk (vertical birefringence). One consequence of media birefringence is the existence of a focus offset between the two distinct best-focus positions for data detection and tracking. The authors present detailed numerical modeling results on the role of substrate birefringence in causing this focus offset.
• Ploessl, R., Chapman, J. N., Scheinfein, M. R., Blue, J. L., Mansuripur, M., & Hoffmann, H. (1993). Micromagnetic structure of domains in Co/Pt multilayers. I. Investigations of wall structure. Journal of Applied Physics, 74(12), 7431-7437.
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  Abstract: An analysis of the micromagnetic structure of domains and domain walls in Co/Pt multilayer films is reported. Magneto-optically written domains have been imaged in a scanning transmission electron microscope by using the modified differential phase contrast mode of Lorentz electron microscopy. These have been compared with computer-simulated images based on a two-dimensional model of a circular, perpendicular magnetized domain with a Bloch-like wall structure. Agreement is found for the domain and stray field contrast, but the absence of wall contrast in the experimental images indicates a more complex wall structure in the multilayer than was assumed by the model. In a further series of calculations the magnetic microstructure of a Co/Pt multilayer was modeled by solving the Landau-Lifshitz-Gilbert equations. These suggest that the wall structure varies throughout the thickness of the multilayer, allowing significant saving of magnetostatic energy through the establishment of flux closure paths close to the walls, and are consistent with experimental observations.
• Wu, T., Hong, F. u., Hajjar, R. A., Suzuki, T., & Mansuripur, M. (1993). Measurement of magnetic anisotropy constant for magneto-optical recording media: A comparison of several techniques. Journal of Applied Physics, 73(3), 1368-1376.
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  Abstract: Experimental data of the intrinsic perpendicular magnetic anisotropy energy constant Ku are presented for amorphous rare earth-transition metal (RE-TM) Tbx(FeCo)1-x and multilayered Co/Pt thin film samples. These data were independently measured using five techniques based on torque magnetometry, the extraordinary Hall effect, and the magneto-optic Kerr effect. In the Hall effect measurement, the external field was applied to the sample in three different ways: fixed at 45°from the film normal; rotating around the sample; and fixed along the in-plane direction. The results obtained with these techniques agree with each other for the Co/Pt samples. However, we do find systematic differences in the measured Ku for the Tb x(FeCo)1-x samples. For example, Ku given by the Hall effect and Kerr effect is always larger (by up to a factor of 3) than that given by torque technique. Another interesting fact is that Ku given by the Hall effect technique drops as x approaches the compensation point xc in the TM-dominant case, but increases as x approaches x c in the RE-dominant case. These experimental results are explained by taking into account the canting between RE and TM subnetworks.
• Hajjar, R. A., & Mansuripur, M. (1992). Magnetoresistance peaks in the neighborhood of coercivity in magneto-optical recording media. Journal of Applied Physics, 72(4), 1528-1538.
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  Abstract: Perpendicular magnetoresistance data performed on magneto-optical samples with uniaxial magnetic anisotropy (perpendicular to the film plane) show a change of the resistance ΔR/R when the applied field reaches the coercive field. The various mechanisms that can lead to this phenomenon are investigated based on different magneto-optical films. In particular, the interaction of magnetic domains and domain walls with the electric current is interesting. Separating the two effects is important to understanding of the various galvanomagnetic and magnetic processes in these films. Three different mechanisms are considered in order to explain the data: The first mechanism is associated with the Hall effect, the second mechanism involves the anisotropic resistivity, and the third mechanism is related to the s-d scattering effect. Some of the experimental results are explained by modeling the current and electric-field distribution in these films. In the simulations the film is modeled by a two- or three-dimensional lattice with each branch in the lattice having its own resistivity tensor in order to simulate magnetic domains and domain walls in the film.
• Hajjar, R. A., Wu, T. H., & Mansuripur, M. (1992). Measurement of anisotropy energy for magneto-optical media. Journal of Applied Physics, 71(2), 813-820.
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  Abstract: A technique is proposed for measuring the anisotropy energy of magneto-optical media. the technique consists of rotating a sample in a fixed external magnetic field and monitoring the extraordinary Hall effect signal of the sample. From the Hall effect signal, the angle of rotation of the sample, and the saturation magnetization of the sample (which is measured separately by a vibrating sample magnetometer), we obtain the anisotropy energy as a function of the deviation of magnetization from the easy axis. The technique is applied to multilayered Co/Pd and Co/Pt films as well as to amorphous rare-earth transition metal TbFeCo alloy films. The anisotropy constants thus obtained are compared with those obtained using other techniques such as torque magnetometry and Hall effect (or Kerr effect) measurements with applied field in the plane of the sample.
• Hong, F. u., & Mansuripur, M. (1992). Boltzmann distribution of bond orientations and perpendicular anisotropy in amorphous rare-earthtransition-metal films. Physical Review B, 45(13), 7188-7195.
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  Abstract: We show that the Boltzmann distribution of bond orientations induced by a perpendicularly magnetized layer in the growth process of an amorphous rare-earthatransition-metal film always leads to the bulk perpendicular magnetic anisotropy, irrespective of the specific functional form of the bond energy. The initial perpendicularly magnetized layer can arise from the surface anisotropy produced by antiparallel dipoles or even from spontaneous magnetization. © 1992 The American Physical Society.
• Hong, F. u., Giles, R., Mansuripur, M., & Patterson, G. (1992). Investigation of the effects of nanostructure on the observable behavior of magnetic thin film using large-scale computer simulation. Computers in physics, 6(6), 610-629.
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  Abstract: Large-scale computer simulations of magneto-optical thin films with nanoscale structures are performed on the Connection Machine. The magneto-optical thin films are modeled by a two-dimensional lattice of magnetic dipoles which follow the Landau-Lifshitz-Gilbert dynamic equation. The effective field on each dipole includes the local anisotropy, the nearest neighbor exchange interactions, the magnetic dipole-dipole interactions, and an externally applied field. The film is divided into many patches (regions) and each patch can have different properties. Four different patchy films are studied. (i) The film has different exchange stiffness constant on the patch borders. (ii) The film has large magnetization, but has zero exchange on the patch borders. (iii) The patches have different easy axis orientations. (iv) The patches have different anisotropy constants. The computer simulations show that films with different kinds of patches have different features in their magnetic behavior. Based on these correspondences between the nanostructure and the magnetic properties, certain features recently observed in several magneto-optical thin films are able to be explained.
• Bernacki, B. E., & Mansuripur, M. (1991). Characterization of magneto-optical recording media in terms of domain boundary jaggedness. Journal of Applied Physics, 69(8), 4960-4962.
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  Abstract: Noise in magneto-optical recording devices can be classified as system-related noise and media noise. Media noise is rooted in the magnetic and magneto-optical properties of the recording media. To investigate media noise and its relation to microstructure and micromagnetics of thin films, the jaggedness of magnetic domain boundaries is characterized using static domain observations in which the fractal dimension D is measured for the domain boundaries. Samples of TbFeCo deposited under similar conditions, but with slightly different compositions, exhibited different amounts of jaggedness, and hence, slightly different values of D, i.e., 1.05≤D≤1.20. Temperature dependent measurements performed on a TbFe sample showed increasing D with increasing temperature, 1.19≤D≤1.28 for 300 K ≤T≤360 K. Possible sources of jaggedness include structural/magnetic inhomogeneities as well as competition between domain-wall energy and demagnetization.
• Giles, R. C., & Mansuripur, M. (1991). Micromagnetics of thin-film CoX media for longitudinal magnetic recording. Journal of Applied Physics, 69(8), 4712-4714.
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  Abstract: We use large-scale computer simulations to model magnetization-reversal dynamics in thin films of sputtered CoX alloys (X=Cr, Pt, etc.). We use full Landau-Lifschitz-Gilbert dynamics to evolve very large (65,536-spin) systems for tens of thousands of time steps. Through such simulations, we are able to relate model micromagnetic parameters to complex phenomena observed experimentally. An important goal is to better understand the role of exchange coupling in the recording dynamics of these media. We present results on the microscopic magnetic states and structures found during reversal in a model CoX material.
• Giles, R. C., Kotiuga, P. R., & Mansuripur, M. (1991). Parallel micromagnetic simulations using Fourier methods on a regular hexagonal lattice. IEEE Transactions on Magnetics, 27(5), 3815-3818.
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  Abstract: Computer simulations of the microscopic magnetic dynamics of thin films provides a means for developing theoretical understanding of the behavior of magnetic recording materials and a way of relating material parameters to magnetic behavior. Such simulations have become possible because of the availability of high-performance supercomputers (such as the Connection Machine) and by improvements in algorithms for evaluating magnetic interactions. The proper implementation of the Fourier technique on a two-dimensional hexagonal lattice is described. A naive transcription of the method as used for a rectangular lattice leads to serious aliasing problems for short wavelengths. The implementation described reduces these effects.
• Hajjar, R. A., Mansuripur, M., & Shieh, H. -. (1991). Measurements of magnetoresistance in magneto-optical recording media. Journal of Applied Physics, 69(10), 7067-7080.
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  Abstract: The magnetoresistance effect in compositionally modulated transition-metal/transition-metal films (Co/Pt and Co/Pd) and in amorphous binary rare-earth-transition-metal alloy films (TbFe) has been investigated. Results of measurements on several samples at room temperature as a function of the strength of the applied magnetic field are reported. For each sample three different configurations are investigated in which the direction of the applied field is (i) perpendicular to the plane of film, (ii) in the plane of the film and parallel to the direction of the electric current, (iii) in the plane of the film and perpendicular to the direction of the current. During these measurements the extraordinary Hall effect and the magneto-optic Kerr effect have also been monitored. This additional information, together with the magnetization measurement results obtained from a vibrating sample magnetometer, are used to analyze the data and to explain some of their interesting features.
• Hajjar, R. A., Mansuripur, M., & Shieh, H. -. (1991). Measurements of the anomalous magnetoresistance effect in Co/Pt and Co/Pd multilayer films for magneto-optical data storage applications. Journal of Applied Physics, 69(8), 4686-4688.
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  Abstract: The anomalous magnetoresistance effect in compositionally modulated TM/TM films (Co/Pt and Co/Pd) has been investigated. Results of measurements on samples at room temperature as a function of the strength of the applied magnetic field are reported. For each sample three different configurations are investigated in which the direction of the applied field is (i) perpendicular to the plane of the film, (ii) in the plane of the film and parallel to the direction of the electric current, (iii) in the plane of the film and perpendicular to the direction of the current. During these measurements the extraordinary Hall effect and the magneto-optical Kerr effect have also been monitored. This additional information, together with the magnetization measurement results obtained from a vibrating sample magnetometer, are used to analyze the data and to explain some of their interesting features.
• Hajjar, R. A., Wu, T., & Mansuripur, M. (1991). Magnetoresistance of Co/Pd and Co/Pt multilayer films for magneto-optical data storage applications. Journal of Applied Physics, 70(10), 6041-6043.
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  Abstract: A study of the galvanomagnetic, magnetic, and magneto-optical properties of multilayered Co/Pd and Co/Pt films is presented. The samples are of different Co content with fixed thickness for the evaporated Co/Pt series and different thickness with fixed composition for the sputtered Co/Pd series. The magnetic and electronic properties of these films are correlated with the magnetoresistance measurements performed with fields applied parallel and perpendicular to the plane of the samples. The s-d scattering observed when the magnetization is aligned with the applied magnetic field is interpreted in terms of the electronic band structure of the materials.
• Mansuripur, M. (1991). Computation of electron diffraction patterns in Lorentz electron microscopy of thin magnetic films. Journal of Applied Physics, 69(4), 2455-2464.
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  Abstract: The vector potential field for a thin magnetic film with arbitrary pattern of magnetization is calculated using fast Fourier transforms. The vector potential is used to compute the phase modulation imparted to the electron beam in Lorentz electron microscopy. Calculated phase patterns and the corresponding intensity distributions for several magnetic configurations of practical interest are described.
• Mansuripur, M. (1991). Enumerative modulation coding with arbitrary constraints and postmodulation error correction coding for data storage systems. Proceedings of SPIE - The International Society for Optical Engineering, 1499, 72-86.
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  Abstract: Modulation constraints of practically any degree of complexity can be described by a state transition table with a finite number approximately $OMEGA of states. Examples include all (d,k;c) codes (where approximately $OMEGA ≤ 2(k + 1)(2c + 1), more general codes with run-length limitations, and run-length limited codes which exclude certain bit-patterns. From the state transition table we construct a trellis diagram for code words of arbitrary length L0. If desired, the trellis may be confined in the beginning and/or at the end to a subset of states. We then show a simple method of enumeration that assigns a number to each code word in the trellis according to its lexicographic order. All the necessary information for enumerative encoding and decoding of binary data will be subsequently stored in an array of size L0 × approximately $OMEGA; both encoding and decoding can be achieved with a few simple operations using this table. In short, arbitrarily long blocks of data can be encoded into sequences that satisfy arbitrary constraints, with algorithms that are easy to implement. Since no additional constraints are imposed, the rates approach Shannon's noiseless channel capacity in the limit of long sequences. Ideas are presented for correction of random errors that occur in modulated sequences, so that errors in readout can be corrected prior to demodulation. These post- modulation error correction codes are necessary when modulation can be corrected prior to demodulation. These post-modulation error correction codes are necessary when modulation code words are long, in which case small errors can destroy large quantities of data. Also introduced in this paper is a simple, efficient algorithm for burst-error-correction. The primary application of the ideas of this paper is in the area of data encoding/decoding as applied in magnetic and optical data storage systems.
• Mansuripur, M., Giles, R., & Patterson, G. (1991). Coercivity of domain-wall motion in thin films of amorphous rare-earth-transition-metal alloys. Journal of Applied Physics, 69(8), 4844-4846.
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  Abstract: Computer simulations of a two-dimensional lattice of magnetic dipoles are performed on the Connection Machine. The lattice is a discrete model for thin films of amorphous rare-earth-transition-metal alloys with application to erasable optical data-storage systems. Simulated dipoles follow the dynamic equation of Landau, Lifshitz, and Gilbert under the influence of an effective magnetic field arising from local anisotropy, near-neighbor exchange, classical dipole-dipole interactions, and externally applied fields. By introducing several types of defects and inhomogeneities in the lattice, we show that the motion of domain walls can be hampered in various ways and to varying degrees.
• Zhou, F. L., Erwin, J. K., & Mansuripur, M. (1991). Spectral measurements of the magneto-optical Kerr rotation and ellipticity in the media of optical recording. Journal of Applied Physics, 69(8), 5091-5093.
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  Abstract: Spectral measurements of Kerr rotation and ellipticity for TbFe and superlattice Co/Pt and Co/Pd samples are obtained by a novel technique. The results of measurements are accurate over a wavelength range of 350 to 1100 nm. The interference effect on the Kerr spectra of the TbFe samples are studied by applying the multilayer analysis program. The reflectivity and Kerr spectra of Co/Pt and Co/Pd superlattice samples are studied to understand the interference effect and the magneto-optic interactions.
• Zhou, F. L., Erwin, J. K., Brucker, C. F., & Mansuripur, M. (1991). Wavelength dependencies of the Kerr rotation angle and ellipticity for the magneto-optical recording media. Journal of Applied Physics, 70(10), 6286-6288.
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  Abstract: Wavelength dependencies of the Kerr rotation angle, ellipticity, and reflectivity are measured for a Co/Pt sample and a series of Co/Pd samples with varying film thicknesses. The interference effects are analyzed by comparing the Kerr spectra of the various Co/Pd samples. The dielectric tensors are measured at 632.8 nm and the thickness dependencies of the Kerr rotation angle, ellipticity, and figure of merit are studied from the experimental and simulated results. The wavelength and thickness dependencies of the magneto-optical properties are studied in order to achieve an understanding of the magneto-optical interactions in the superlattice samples.
• Hajjar, R. A., Zhou, F. L., & Mansuripur, M. (1990). Magneto-optical measurement of anisotropy energy constants on amorphous rare-earth transition-metal alloys. Journal of Applied Physics, 67(9), 5328-5330.
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  Abstract: Measurements of the magneto-optic polar Kerr effect are performed on samples with perpendicular magnetization using in-plane magnetic fields. The magnetic anistropy constants are then determined from these measurements. The applied in-plane magnetic field varies from -20 to 20 kOe. Samples are mounted in a temperature-controlled chamber whose temperature is varied in the range of 80-475 K. In the theoretical model the anisotropy energy is expressed as the sum of terms containing sin2 φ and sin4 φ with two anisotropy constants, K1 and K2, to be determined. By matching the theoretical curves with the experimental data, we obtain two functions α(T) and β(T), which are the normalized values of K 1(T) and K2(T) with respect to the saturation magnetization Ms(T).
• Mansuripur, M. (1990). Analysis of multilayer thin-film structures containing magneto-optic and anisotropic media at oblique incidence using 2×2 matrices. Journal of Applied Physics, 67(10), 6466-6475.
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  Abstract: A complete analysis of multilayer structures containing an arbitrary number of dielectric, metal, magnetic, and birefringent/dichroic layers is presented. An algorithm, based on simple 2×2 matrices, is derived which allows reflection, transmission, absorption, magneto-optic conversion, birefringence, and dichroism of the structure to be computed on a personal computer. The incident beam is assumed to be plane monochromatic with arbitrary angle of incidence. There are no approximations involved, and the results are direct consequences of Maxwell's equations.
• Mansuripur, M. (1990). Computer modeling of optical storage media and systems. Proceedings of SPIE - The International Society for Optical Engineering, 1316, 70-80.
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  Abstract: In this article we have reviewed the state of the art in theoretical and computer modeling of the read/write/erase processes in optical data storage systems. Examples have been presented of the types of feasible calculations with the present levels of understanding and with the existing computers. Also a modest attempt has been made to provide guidelines for future research in this area.
• Mansuripur, M., & Giles, R. (1990). Simulation of magnetization reversal dynamics on the Connection Machine (invited) (abstract). Journal of Applied Physics, 67(9), 5555-.
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  Abstract: Magnetization reversal processes in thin magnetic films have been simulated on the Connection Machine (CM). The massive parallelism of the CM allows large lattices of dipoles to interact while following the dynamic equation of Landau-Lifshitz and Gilbert toward equilibrium. Our two-dimensional hexagonal lattice consists of 256×256 dipoles with local uniaxial anisotropy, nearest-neighbor Heisenberg exchange, and long-range dipole-dipole (demagnetizing) interactions. The demagnetizing field has been computed with the fast Fourier transform technique1 which is particularly suited for the CM environment. Two sets of material parameters are considered in these studies. The first set is representative of amorphous rare earth-transition metal (RE-TM) alloys, which are currently of interest for their application as the media of erasable optical data storage. The second set corresponds to polycrystalline cobalt alloys (such as CoCr and CoPt), which are high-quality materials for in-plane magnetic recording applications. The discrete models of the RE-TM films have a cell size of approximately 10 Å, accomodating the narrow wall width of these media. In contrast, the cell size for CoCr-type media is typically 500 Å, which is their average crystallite size. We present simulation results that show domain nucleation and growth processes during magnetization reversal. Hysteresis loops and torque curves have also been computed by simulation, and we show the close agreement between these results and those of experiments. Complex magnetic ripple structures are observed in CoCr-type media when random axis anisotropy competes with demagnetization. Some of the more interesting features of these simulation ripples will be described.
• Hajjar, R., & Mansuripur, M. (1989). Mean-field analysis of ternary and quaternary rare earth-transition metal alloys for thermomagnetic recording. IEEE Transactions on Magnetics, 25(5), 4021-4023.
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  Abstract: A mean-field model for rare-earth-transition-metal RE-TM alloys developed to analyze ternary (TbFeCo) and quaternary (TbGdFeCo, TbDyFeCo) alloys of interest in thermomagnetic recording is described. The model is based on the localized mean-field theory and emphasizes the reduction of adjustable parameters. The experimental magnetization versus temperature curves are compared to the model predictions, and good agreement is obtained in all cases. The exchange parameters and atomic moment values obtained are consistent with the current understanding of these alloys. The possibility of including an intinerant model to account for the 3d transition-metal magnetic electrons is considered.
• Mansuripur, M. (1989). Certain computational aspects of vector diffraction problems. Journal of The Optical Society of America A-optics Image Science and Vision, 6(6), 786-805. doi:10.1364/josaa.6.000786
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  Fourier decomposition of a given amplitude distribution into plane waves and the subsequent superposition of these waves after propagation is a powerful yet simple approach to diffraction problems. Many vector diffraction problems can be formulated in this way, and the classical results are usually the consequence of a stationary-phase approximation to the resulting integrals. For situations in which the approximation does not apply, a factorization technique is developed that substantially reduces the required computational resources. Numerical computations are based on the fast-Fourier-transform algorithm, and the practicality of this method is shown with several examples.
• Mansuripur, M. (1989). Computation of fields and forces in magnetic force microscopy. IEEE Transactions on Magnetics, 25(5), 3467-3469.
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  Abstract: In magnetic force microscopy (MFM), a sharp magnetic needle interacts with the field pattern established by the sample near its surface. A cantilever then converts the force on the needle to a displacement, which is measured interferometrically or otherwise. The author describes a model for the tip that takes full account of the micromagnetic interactions involved. The stray magnetic field for a thin film is computed, and the micromagnetic model of the needle is developed. An example calculation is given to illustrate the application of the model.
• Mansuripur, M. (1989). Demagnetizing field computation for thin films: Extension to the hexagonal lattice. Journal of Applied Physics, 66(8), 3731-3733.
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  Abstract: A previously published method of calculating the magnetic field pattern of thin films using fast Fourier transforms is extended to situations where the magnetization distribution is specified on a hexagonal lattice.
• Mansuripur, M. (1989). Detecting transition regions in magneto-optical disk systems. Applied Physics Letters, 55(8), 716-717.
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  Abstract: Several combinations of incident polarization and detection schemes suitable for direct detection of transitions in magneto-optical disk systems are described. One such combination uses a circularly polarized light with a single split detector in the far field. Another scheme uses linear polarization in conjunction with differential detection. In the first scheme the medium must be optimized for Kerr rotation while the second method requires maximum ellipticity.
• Mansuripur, M. (1989). Domain wall energy in the media of magneto-optical recording. Journal of Applied Physics, 66(12), 6175-6176.
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  Abstract: A method of calculating domain wall energy density from experimental observations is proposed. The technique requires measurement of the expansion and collapse fields for circular domains of arbitrary size.
• Mansuripur, M. (1989). On the self-magnetostatic energy of jagged domain walls. Journal of Applied Physics, 66(8), 3727-3730.
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  Abstract: The demagnetizing energy of thin magnetic films can be written in terms of the Fourier components of the magnetization distribution. This formalism is used to investigate the structure of jagged domain walls in both perpendicular and in-plane media. Also introduced is a set of correlation functions and their relationship to demagnetizing energy density in media with random magnetization distribution.
• Calkins, J. R., Ruane, M. F., & Mansuripur, M. (1988). System for measurement of domain wall motion in amorphous rare earth-transition metal alloys. IEEE Transactions on Magnetics, 24(6), 2314-2316.
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  Abstract: A system has been developed for measuring domain-wall motion in amorphous rare-earth-transition-metal alloys. A one-dimensional scanning technique is utilized in which a focused, oscillating HeNe laser spot moves over the magnetization pattern in the film. Domain walls are detected through the polar Kerr effect as the spot scans the film. A magnetic field is applied to the film in order to move the domain walls. The maximum line-scanning rate is about 250 Hz. The spot diameter at a 632.8-nm wavelength is limited to about 8 μm by the 0.46 numerical aperture of the focusing objective, the beam waist of the laser, and aberrations. The domain wall position can be measured to within ±1 μm. The apparatus is described, and the results domain-wall-motion measurements are presented.
• Mansuripur, M. (1988). Magnetization reversal dynamics in the media of magneto-optical recording. Journal of Applied Physics, 63(12), 5809-5823.
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  Abstract: Domain wall dynamics in thin films of amorphous rare-earth-transition-metal alloys are investigated using numerical integration of the Landau-Lifshitz- Gilbert equation. A two-dimensional square lattice of dipoles with nearest-neighbor exchange interaction and random axis anisotropy is simulated and the structure of domain walls (with and without Bloch lines) is determined. The motion of domain walls under applied fields is then considered and the effects of random spatial variations of magnetic parameters upon wall mobility are discussed.
• Mansuripur, M., & Giles, R. (1988). Demagnetizing field computation for dynamic simulation of the magnetization reversal process. IEEE Transactions on Magnetics, 24(6), 2326-2328.
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  Abstract: The magnetic-field distribution for a thin magnetic film is computed using the fast Fourier transform technique. The method is quite general and accommodates any two-dimensional magnetization distribution. It allows the computation of fields both inside the film (demagnetizing fields) and outside (stray fields and leakage).
• Mansuripur, M., & McDaniel, T. W. (1988). Magnetization reversal dynamics in magneto-optic media (invited). Journal of Applied Physics, 63(8), 3831-3834.
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  Abstract: Dynamics of magnetization reversal in thin films of amorphous rare earth-transition metal alloys are investigated. Using computer simulations for a two-dimensional square lattice of dipoles with nearest-neighbor exchange interaction and random axis anisotropy, the Landau-Lifshitz-Gilbert equation is numerically integrated to yield the static wall structure and its motion under an applied field. The simulated results show excellent agreement with theory in the special cases where analytic solutions exist.
• Uber, R. E., & Mansuripur, M. (1988). Magneto-optical measurement of anisotropy energy constant(s) for amorphous rare earth, transition metal alloys. IEEE Transactions on Magnetics, 24(6), 2461-2463.
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  Abstract: Measurements of the anisotropy energy constants of rare-earth -transition-metal (RE-TM) thin films at temperatures from ambient to 150°C are reported. An in-plane magnetic field (up to 16.5 kOe) is applied to a saturated sample with perpendicular magnetization. The movement of magnetiztion away from the perpendicular direction is monitored using the polar Kerr effect. Due to the limited penetration depth of light at the HeNe wavelength of 632.8 nm, the Kerr effect is principally due to the top 500 angstrom of the transition metal subnetwork in the films.
• Calkins, J., Mansuripur, M., & Ruane, M. (1987). MAGNETIZATION REVERSAL IN AMORPHOUS TbFe FILMS.. Materials Research Society Symposia Proceedings, 80, 435-441.
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  Abstract: Observations under polarized light of magnetization reversal in thin amorphous films of TbFe alloys indicate that the reversal process is initiated at inherent nucleation sites where reverse-magnetized domains appear at fields below coercivity. The nuclei then grow in time until they cover the entire sample. The process of nucleation and growth seems to be dominated by the microstructure, since samples with identical bulk magnetic characteristics (such as composition, hysteresis loop and coercivity) exhibit quite different reversal behavior. This process is also dependent upon the history of magnetization of the sample.
• Chakravartty, D., Mansuripur, M., & Ruane, M. F. (1987). DEPOSITION, CHARACTERIZATION, AND MAGNETO-OPTICAL PROPERTIES OF AMORPHOUS TbFe ALLOYS.. Materials Research Society Symposia Proceedings, 80, 429-434.
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  Abstract: Amorphous films of Tb//xFe//1// minus //x are prepared by simultaneous RF bias sputtering onto various substrates and the hysteresis loops of the resulting samples are obtained both by magneto-optical and VSM loop tracers. The coercivities of the samples deposited in the same run but onto different substrates are observed to be somewhat different and these differences are discussed in light of the current understanding of the deposition process.
• Mansuripur, M. (1987). Analysis of astigmatic focusing and push-pull tracking error signals in magnetooptical disk systems.. Applied optics, 26(18), 3981-6. doi:10.1364/ao.26.003981
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  Methods of geometrical optics are used in deriving a simple expression for the focus error signal in terms of the parameters of an astigmatic system. The extent of validity of this result is then examined by comparison with diffraction calculations. Diffraction analysis also permits the study of push-pull tracking error signal from pregrooved disk surfaces.
• Mansuripur, M. (1987). Coercivity and its role in thermomagnetic recording. Journal of Applied Physics, 61(8), 3334-3336.
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  Abstract: A model is proposed for the mechanism of magnetization reversal in thin films of amorphous rare-earth-transition-metal alloys. The model exhibits the observed features of the magnetization reversal process, coercivity and the processes of thermomagnetic recording and erasure.
• Mansuripur, M. (1987). Magnetization reversal, coercivity, and the process of thermomagnetic recording in thin films of amorphous rare earth-transition metal alloys. Journal of Applied Physics, 61(4), 1580-1587.
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  Abstract: A model is proposed for the mechanism of magnetization reversal in thin films of amorphous alloys with perpendicular magnetic anisotropy. Examples of these alloys are TbFe, GdCo, DyFe, and GdTbFeCo, which are currently under investigation as storage media for erasable optical recording applications. The model exhibits the observed behavior of the media such as nucleation and growth of reverse-magnetized domains under external magnetic fields; square hysteresis loops; temperature dependence of coercivity; formation and stability of domains under conditions of thermomagnetic recording; and incomplete erasure with insufficient applied fields.
• McDaniel, T. W., & Mansuripur, M. (1987). NUMERICAL SIMULATION OF THERMOMAGNETIC WRITING IN RE-TM FILMS.. IEEE Transactions on Magnetics, MAG-23(5), 2943-2945.
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  Abstract: We have developed a simplified micromagnetics simulation of the behavior of RE-TM films that produces an equilibrium configuration of film magnetization for a specified thermal profile and applied magnetic field. This Monte Carlo-type model is useful for assessing the size, shape, and stability of written marks in MO recording. In addition, the simulation provides estimates of the minimum field strength required for nucleation and growth of reversed domains, and hence it predicts film coercivity at any temperature. An equilibrium state is determined by magnetic energy minimization. Magnetization dynamics are not incorporated into the model, but instead, a quasi-static approach to equilibrium is simulated. Spatial resolution can be arbitrarily small, and discretization down to about 20 nm can be reasonably accommodated. Readout of written domains has been incorporated as an additional feature of this model.
• Ruane, M., Jain, A., Rosenvold, R., & Mansuripur, M. (1987). DIELECTRIC TENSOR CHARACTERIZATION FOR OVERCOATED AMORPHOUS TbFe ALLOYS.. Materials Research Society Symposia Proceedings, 80, 401-408.
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  Abstract: Amorphous thin films of TbFe, sputter-deposited on quartz substrates with compositions supporting polar Kerr magneto-optical behavior and overcoated with a transparent protective layer, are studied to determine their dielectric tensor elements. Reflectivity measurements over a range of angles of incidence are made in an apparatus that corrects for the overcoat layer and exploits magnetization reversal to enhance the measurement of r// PERPEND , the complex reflectivity associated with the magneto-optical signal. Conventional Fresnel reflectivities are also found. The theoretical model for reflectivities from a thick film magneto-optical medium at oblique incidence is developed and used within a Lavenberg-Marquardt nonlinear estimation algorithm to estimate sequentially the dielectric tensor elements, considering their widely varying magnitudes and sensitivities to errors in reflectivity data. The interpretation of the dielectric elements in terms of magneto-optical performance and structural perpendicular anisotropy is discussed.
• Mansuripur, M. (1986). Figure of merit for magneto-optical media based on the dielectric tensor. Applied Physics Letters, 49(1), 19-21.
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  Abstract: A figure of merit is derived for the magneto-optical media used in erasable optical data storage. It is shown that the ratio of the useful signal generated by the polar Kerr effect to the incident laser power is always below the figure of merit, but the figure can be approached if the magneto-optic medium is embedded in a proper multilayer structure.
• Mansuripur, M., & Ruane, M. F. (1986). MEAN-FIELD ANALYSIS OF AMORPHOUS RARE EARTH-TRANSITION METAL ALLOYS FOR THERMOMAGNETIC RECORDING.. IEEE Transactions on Magnetics, MAG-22(1), 33-43.
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  Abstract: A mean-field model is developed for amorphous ferromagnetic materials with potential applications in thermomagnetic recording/magneto-optical readout systems. The emphasis is on the reduction of the number of adjustable parameters, so that important variables and their effects on magnetic properties can be investigated. The available experimental data on GdCo-, GdFe-, and TbFe-based alloys are compared with the model predictions, and good agreement is obtained in all cases. Expressions for the exchange stiffness coefficient and macroscopic anisotropy energy constant are derived and the latter is compared with available experimental data. The results have been used to study domain wall characteristics of the three material systems.
• Mansuripur, M., Ruane, M., Wolniansky, P., Chase, S., & Rosenvold, R. (1986). MAGNETO-OPTICAL PROPERTIES OF AMORPHOUS TbFe ALLOYS.. Materials Research Society Symposia Proceedings, 58, 181-184.
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  Abstract: Hysteresis loops and anisotropy energy constants are measured in a magneto-optical system that combines Kerr rotation and ellipticity to enhance signal strength. Temperature dependence of the polar Kerr effect is compared with the magnetization of the iron subnetwork in the mean-field approximation and good agreement is obtained. Perpendicular magnetic anisotropy is studied by magneto-optical methods, yielding the first two coefficients of the series expansion of anisotropy energy in terms of the angle of deviation from the easy axis.
• Wolniansky, P., Chase, S., Rosenvold, R., Ruane, M., & Mansuripur, M. (1986). Magneto-optical measurements of hysteresis loop and anisotropy energy constants on amorphous Tb_xFe_1-x alloys. Journal of Applied Physics, 60(1), 346-351.
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  Abstract: Measurements of the Kerr magneto-optic effect, coercivity, and anisotropy energy constants are performed in a magneto-optical system that combines the Kerr rotation angle and ellipticity to enhance the strength of the signal. The temperature dependence of the polar Kerr effect is compared with the magnetization of the iron subnetwork in the mean-field approximation and good agreement is obtained in all cases. Coercivity is found to be a strong function of the sweeping frequency and the saturating field and the results are found to be in qualitative agreement with the magnetization reversal model based on the existence of initial nuclei in a saturated film and the subsequent growth of these nuclei under a reverse field. Finally, perpendicular magnetic anisotropy energy is studied by magneto-optical techniques and the first two coefficients in the expansion of anisotropy energy in powers of the angle of deviation from the easy axis are determined.
• Mansuripur, M., Ruane, M. F., & Horenstein, M. N. (1985). ERASABLE OPTICAL DISKS FOR DATA STORAGE: PRINCIPLES AND APPLICATIONS.. Industrial & Engineering Chemistry, Product Research and Development, 24(1), 80-84.
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  Abstract: Erasable optical disk storage systems offering densities in excess of 10**8 bits/cm**2 using thermomagnetic recording and magnetooptic readout are described and compared to conventional magnetic disks. The preparation and properties of amorphous rare earth-transition metal alloy thin films, which serve as the recording media, are also presented. The lack of a strong readout signal suggests the need for the enhancement of the signal-to-noise ratio (snr). A multilayering scheme with improved snr and superior thermal characteristics is discussed. Potential research and development issues are also indicated.
• Mansuripur, M., Ruane, M. F., & Horenstein, M. N. (1985). MAGNETIC PROPERTIES OF AMORPHOUS RARE EARTH-TRANSITION METAL ALLOYS FOR ERASABLE OPTICAL STORAGE.. Proceedings of SPIE - The International Society for Optical Engineering, 529, 25-32.
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  Abstract: A mean-field model for amorphous rare earth-transition metal (RE-TM) alloys is developed and compared with available experimental data on GdCo-, GdFe- and TbFe- based alloys. The model assumes the existence of two iron subnetworks, one with ferromagnetic and the other with antiferromagnetic exchange coupling. The fraction of iron ions in each subnetwork and the magnetic moment of the TM ion are the only adjustable parameters of the model. Good agreement is obtained in all cases between the model calculations and the experimental data. Preliminary measurements of the magneto-optic Kerr effect on TbFe samples are also reported and the results are compared with the mean-field model predictions. A phenomenological model for the anisotropy energy density constant is proposed and the results are tied to the mean-field model for calculations of domain wall properties. (Edited author abstract. )
• Mansuripur, M., Ruane, M. F., & Horenstein, M. N. (1985). MATERIALS FOR MAGNETO-OPTICAL DATA STORAGE.. Polymeric Materials Science and Engineering, Proceedings of the ACS Division of Polymeric Material, 53, 605-.
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  Abstract: Amorphous rare earth-transition metal (RE-TM) alloys are currently the most promising media for erasable optical data storage. Thin films of these alloys can be deposited on relatively large substrates by both vacuum evaporation and sputtering and can exhibit desirable recording characteristics such as uniformity of structure, lack of grains and crystallites, perpendicular magnetic anisotropy and large magnetic coercivity. The structural and magnetic properties of the films are strongly dependent on the deposition environment and in the case of sputter deposited films for example, vary with the argon pressure, substrate temperature and the substrate bias voltage. These dependencies are discussed in the light of new theoretical and experimental results.
• Mansuripur, M. (1984). DISK STORAGE: MAGNETOOPTICS LEADS THE WAY.. Photonics Spectra, 18(10), 59-60, 62.
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  Abstract: This article describes the principle of magnetooptic disk storage. It is an extension of current optical disk technology that will add erasability to the features of present optical storage devices. The feasibility of the concept has been confirmed in recent years by the development of several prototype systems in the US, Europe and Japan.
• Mansuripur, M. (1984). HIGH-DENSITY MAGNETO-OPTICAL DISK STORAGE AND THE EFFECT OF FINITE BEAM SIZE IN READOUT.. Journal of Applied Physics, 56(4), 1165-1170.
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  Abstract: A method of data reconstruction from a digital magneto-optical disk system with diffraction-limited spot size is described. Using a linear filter with high-frequency enhancement we show that significant improvements in the storage capacity can be achieved at a reasonable cost in terms of the signal-to-noise ratio. Performance is evaluated against an optimum but impractical method as well as a technique for the reconstruction of the analog waveforms.
• Mansuripur, M., & Connell, G. A. (1984). ENERGETICS OF DOMAIN FORMATION IN THERMOMAGNETIC RECORDING.. Journal of Applied Physics, 55(8), 3049-3055.
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  Abstract: A new model for the distribution of perpendicular magnetization in thin magnetic films supporting a circular domain is proposed. The contributions of various sources to the magnetic energy are determined and the demagnetizing effect in particular is discussed at length. It is shown that a demagnetizing energy density per unit area of the domain wall can be defined which, unlike the domain wall energy density arising from exchange and anisotropy contributions, is a function of film thickness h. For domains of large radius and small wall thickness (compared with h), the demagnetizing energy density is found to be linearly increasing with h. A typical cycle of thermomagnetic recording on a thin ferrimagnetic film with room temperature compensation point is then studied, and the effect of various parameters on the formation process and stability of reverse magnetized domains is discussed.
• Chen, T., Mansuripur, M., & Malmhall, R. (1983). THICKNESS DEPENDENCE OF MAGNETO-OPTIC EFFECTS IN TERBIUM-IRON FILMS.. Proceedings of SPIE - The International Society for Optical Engineering, 382, 260-263.
• Chen, T., Mansuripur, M., & Malmhall, R. (1983). THICKNESS DEPENDENCE OF MAGNETO-OPTIC EFFECTS IN Tb-Fe FILM.. Array, THA5. 1-THA5. 3.
• Connell, G. A., Allen, R., & Mansuripur, M. (1983). Interference enhanced Kerr spectroscopy for very thin absorbing films - Application to amorphous terbium iron. Journal of Magnetism and Magnetic Materials, 35(1-3), 337-339.
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  Abstract: A new method of obtaining polar Kerr spectra from very thin absorbing films is used to study the thickness dependence of the Curie temperature, compensation temperature and critical behavior of the Fe-subnetwork of amorphous Tb-Fe alloy films. Significant deviations from bulk behavior begin to occur a thickness below about 20 nm. © 1983.
• Connell, G. A., Treves, D., Allen, R., & Mansuripur, M. (1983). Signal-to-noise ratio for magneto-optic readout from quadrilayer structures. Applied Physics Letters, 42(8), 742-744.
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  Abstract: We present an experimental investigation of our earlier theoretical predictions regarding the signal-to-noise ratio for magneto-optic readout from quadrilayer structures in a differential detection scheme. Using quadrilayer structures employing amorphous Tb-Fe alloys as the magnetic material, quartz as the dielectric material, and aluminum as the reflecting material, we show that the signal enhancement predicted for quadrilayers occurs even when the numerical aperture of the readout system is large, a crucial result for their effectiveness in magneto-optic storage applications. We also show that the signal-to-noise ratios measured are in quantitative agreement with theory.
• Mansuripur, M. (1983). Orientational effect of the extensional flow field on solutions of rigid rodlike macromolecules-disappearance of the isotropic to nematic phase transition. International Journal of Multiphase Flow, 9(3), 299-307.
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  Abstract: The effect of steady state uniaxial extensional flow on a solution of rigid rodlike macromolecules is theoretically studied. The mean field theory of Maier and Saupe is extended to cover situations in which the macromolocular solution is subjected to an extensional flow field. It is found that for a given solution a critical flow gradient exists beyond which the first order nematic-isotropic phase transition, which is typical of such solutions in the absence of flow, disappears. A similar result is obtained when the theory of Onsager is applied to the problem. Order parameter as a function of flow gradient is calculated and it is shown that the contribution of flow to the ordering of macromolecules is most significant when the stationary solution is isotropic but close to the transition point. © 1983.
• Mansuripur, M., & Connell, G. A. (1983). LASER-INDUCED LOCAL HEATING OF MOVING MULTILAYER MEDIA.. Applied Optics, 22(5), 666-670.
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  PMID: 18195853;Abstract: Earlier work on the local heating of stationary multilayer structures by focused laser light has been extended to deal with nonstationary situations. the numerical procedures described here are therefore applicable to many important technologies including optical recording, thermal marking, and laser annealing. We demonstrate this in two examples, namely, the effects of readout intensity on the readout signal from a quadrilayer magnetooptic disk and the writing theshold for ablative materials in single-layer and three-layer structures.
• Mansuripur, M., & Connell, G. A. (1983). MAGNETO-OPTICAL RECORDING.. Proceedings of SPIE - The International Society for Optical Engineering, 420, 222-230.
• Mansuripur, M., & Connell, G. A. (1983). THERMAL ASPECTS OF MAGNETO-OPTICAL RECORDING.. Journal of Applied Physics, 54(9), 4794-4798.
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  Abstract: The authors discuss the influence of thermal response on the magneto-optic readout performance of optically similar but thermally different quadrilayer media, using newly developed computational techniques for examining laser-induced heat flow in moving multilayer media. The importance of time scale for differentiating the write and read processes is emphasized. It is then shown that the optimum design is a function of the medium velocity and available laser power for writing and is not normally one that provides maximum signal-to-noise ratio in the limit that laser heating during readout can be ignored. Finally, a systematic approach to the selection of the best quadrilayer design for a given set of system conditions is given.
• Connell, G. A., Allen, R., & Mansuripur, M. (1982). MAGNETO-OPTICAL PROPERTIES OF AMORPHOUS TERBIUM-IRON ALLOYS.. Journal of Applied Physics, 53(11 Pt 2), 7759-7761.
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  Abstract: The magneto-optical properties of rf sputtered amorphous Tb//xFe//1// minus //x alloys (with 0. 17 less than equivalent to x less than equivalent to 0. 32) were investigated using reflectivity and polar Kerr measurements from a surface overcoated in situ with SiO//2. The concentration dependence of the Curie temperature, compensation temperature, and low-temperature polar Kerr amplitude were all derived and the results compared with a mean-field theory. The temperature behavior of the coercive force was also determined. While a considerable degree of agreement is obtained with earlier work, it appears that the low-temperature polar Kerr amplitude can only be determined by the iron sub-network alone, if the iron moment increases with terbium concentration. The extent to which this view is justified is examined in light of current ideas.
• Mansuripur, M. (1982). MAGNETIZATION REVERSAL IN THIN MAGNETIC FILMS WITH PERPENDICULAR ANISOTROPY.. Journal of Applied Physics, 53(3 pt 1), 1660-1663.
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  Abstract: A one-dimensional theory of magnetization reversal in thin, perpendicularly anisotropic magnetic films is presented. It is postulated that the presence of a defective point creates an infinitely deep, infinitely narrow potential well which inhibits the rotation of local magnetization. The interval D between neighboring defects, the saturation magnetization M//s, the anisotropy constant K//u, and the exchange energy constant A are assumed to be finite and uniform across the film. Starting with an initial state where the film is uniformly magnetized to saturation in the easy direction, we show that a discontinuous change of state occurs when the reverse external field H reaches a critical value H//c. The domains thus nucleated at the critical field expand to cover the entire area of the film as H increases beyond H//c. Using the normalized values of H and D, defined, respectively, as h equals H/(2K//u/M//s) and d equals D/(4A/K//u)**1**/**2, it is shown that the critical field h//c is a function only of d and that its value decreases significantly as d increases.
• Mansuripur, M., Connell, G. A., & Goodman, J. W. (1982). SIGNAL AND NOISE IN MAGNETO-OPTICAL READOUT.. Journal of Applied Physics, 53(6), 4485-4494.
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  Abstract: For a magneto-optical readout system which employs the Kerr effect, the power spectral density of the read signal has been derived. The noise components originating in the photodetection and amplification stages appear as additive terms in the expression for the overall spectral density, enabling us to define a signal to noise ratio for the readout system. Adjustable parameters of the system are then optimized and a multilayer disk structure is introduced which enhances the Kerr effect and, consequently, results in an increased signal to noise ratio.
• Mansuripur, M., Connell, G. A., & Treves, D. (1982). OPTIMUM DISK STRUCTURES AND ENERGETICS OF DOMAIN FORMATION IN MAGNETO-OPTICAL RECORDING.. IEEE Transactions on Magnetics, Mag-18(6), 1241-1243.
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  Abstract: A quadrilayer magnetooptical device in which the magnetic medium is sandwiched between two dielectric layers and supported by a reflecting substrate is shown to have desirable characterisitics for the storage and retrieval of information. The quadrilayer exhibits a readout snr of about 8 (3) db over the readout from bare (coated) bulk material. At the same time, the writing sensitivity is matched to the available laser power for recording, thus permitting high levels of read power without loss in resolution. Energetics of domain formation in a ferrimagnetic material during a typical write cycle is examined. Contributions from different sources of energy are compared and the role of coercivity in the formation and stability of domains is discussed.
• Mansuripur, M., Connell, G., & Goodman, J. W. (1982). LASER-INDUCED LOCAL HEATING OF MULTILAYERS.. Applied Optics, 21(6), 1106-1114.
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  PMID: 20389812;Abstract: For a multilayer structure illuminated by a laser beam, absorption of optical energy in the absorptive layers and the diffusion of the resultant heat throughout the structure are studied. Analytical and numerical procedures for this study are described, and, as a specific example, the profiles of temperature distribution during recording on a magnetooptical disk are presented. The technique is also expected to be of value for studies of thermal marking and laser annealing.
• Mansuripur, M., Goodman, J. W., Rawson, E. G., & Norton, R. E. (1980). FIBER OPTICS RECEIVER ERROR RATE PREDICTION USING THE GRAM-CHARLIER SERIES.. IEEE transactions on communications systems, COM-28(3), 402-407.
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  Abstract: This paper applies the Gram-Charlier series method to the calculation of error probabilities in digital optical receivers. This method allows the calculation of ″exact″ error probabilities including the effects of avalanche noise, thermal noise, and arbitrary postdetection processing filter. The predictions of this method are compared with those of a simple Gaussian approximation and with the Chernoff bounds. Finally, the effects of modal noise are included in the theory, and some specific cases are explored numerically.

Proceedings Publications

• Mansuripur, M. (2020). An exact derivation of the Thomas precession rate using the Lorentz transformation. In Spintronics XIII, 11470.
• Mansuripur, M. (2020). Dispersion of electromagnetic waves in linear, homogeneous, and isotropic media. In Roland V. Shack Memorial Session: A Celebration of One of the Great Teachers of Optical Aberration Theory, 11479.
• Mansuripur, M. (2020). Energy, linear momentum, and spin and orbital angular momenta of circularly polarized Laguerre-Gaussian wave-packets. In Optical Trapping and Optical Micromanipulation XVII, 11463.
• Spalding, G. C., Mansuripur, M., & Dholakia, K. (2017). Angular momentum exchange between light and small particles (Conference Presentation). In Optical Trapping and Optical Micromanipulation XIV, 10347.
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  We present a few simple examples to illustrate certain fundamental properties of the EM field. Using elementary physical concepts, we explain the nature of interactions that involve exchanges of energy, linear momentum, and angular momentum between EM fields and material media. First, the radiation force experienced by a small, polarizable particle which has a predetermined dielectric susceptibility will be examined. The dielectric susceptibility of small spherical particles will be related to their refractive index (with proper accounting for the effects of radiation resistance). We describe the relation between the energy and orbital angular momentum of a cylindrical harmonic EM wave trapped inside a hollow cylindrical cavity, and explore the relations among the energy, linear momentum, and angular momentum picked up by a small particle under illumination by a cylindrical harmonic EM wave. In light of this analysis, it becomes clear why a small particle spins around its own axis when illuminated by a light beam that carries spin angular momentum, whereas the same particle tends to orbit around an axis of vorticity when exposed to a beam (such as a vector cylindrical harmonic) that possesses orbital angular momentum.
• Mansuripur, M. (2016, February). Light-Matter Interaction: Conversion of Optical Energy and Momentum to Mechanical Vibrations and Phonons. In SPIE Photonics West.
• Mansuripur, M. (2015, August). Sol-gel deposition and plasma treatment of intrinsic, aluminum-doped, and gallium-doped zinc oxide thin films as transparent conductive electrodes. In SPIE Optics & Photonics.
• Mansuripur, M. (2015, February). Electric and Magnetic Dipoles in the Lorentz and Einstein-Laub Formulations of Classical Electrodynamics. In Proceedings of SPIE.
• Mansuripur, M. (2015, September). Energy and linear and angular momenta in simple electromagnetic systems. In SPIE optics & Photonics.
• Mansuripur, M. (2015, September). Tutorial: Opto-mechanical cooling by the back-action of cavity photons,. In SPIE Optics & Photonics.
• Mankowski, T. S., Zhu, Z., Balakrishnan, K., Shikoh, A. S., Touati, F., Benammar, M. A., Mansuripur, M., & Falco, C. M. (2014, August). Metal nanowire-graphene composite transparent electrodes. In Proceedings of SPIE, 9177, 91770I~1:6.
• Mansuripur, M. (2014, August). Advances in Macromolecular Data Storage. In Proceedings of SPIE, 9201, 92010A~1-6.
• Mansuripur, M. (2014, August). Electromagnetic force and torque in Lorentz and Einstein-Laub formulations. In Proceedings of SPIE, 9164, 91640B~1-16.
• Mansuripur, M. (2014, August). Mechanical effects of light on material media: radiation pressure and the linear and angular momenta of photons. In Proceedings of SPIE, 9186, 91860S~1-6.
• Mansuripur, M. (2014, August). On the Electrodynamics of Moving Permanent Dipoles in External Electromagnetic Fields. In Proceedings of SPIE - The International Society for Optical Engineering, 9164, 91640B~1-16.
• Mansuripur, M. (2014, August). The Charge-Magnet Paradoxes of Classical Electrodynamics. In Proceedings of SPIE, 9167, 91670J~1:12.
• Zhu, Z., Mankowski, T. S., Balakrishnan, K., Shikoh, A. S., Touati, F., Benammar, M. A., Mansuripur, M., & Falco, C. M. (2014, August). Transparent conducting electrodes based on thin, ultra-long copper nanowires and graphene nano-composites. In Proceedings of SPIE, 9177, 91770J~1:6.
• Mansuripur, M. (2009). Can future storage technologies benefit from existing or emerging nano-tools and techniques?. In Optical Data Storage 2009, 7505.
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  Certain ideas and techniques are being developed outside the field of optical/magnetic/ electronic recording, but the storage community could benefit from these developments once we become sufficiently familiar with the new concepts and methodologies. Developments in the areas of nano- and bio-photonics, fluorescence microscopy, quantum-dots, optical tweezers, micro- and nano-fluidics, femtosecond lasers, etc., have the potential to influence future generations of data storage systems.
• Peyghambarian, N., Polynkin, P., Polynkin, A., Peyghambarian, N., Moloney, J. V., & Mansuripur, M. (2006). All-Fiber Source of High-Power Picosecond Pulses at 1.5 μm Using Short and Heavily Doped Phosphate-Fiber Amplifier. In Optical Amplifiers and Their Applications/Coherent Optical Technologies and Applications.
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  We report an all-fiber source of high-power picosecond pulses at 1.5µm. Rapid amplification in heavily-doped phosphate fiber produces pulses with peak power of 16.6kW while pulse distortion is minimal in either temporal or spectral domain.
• Peyghambarian, N., Polynkin, P., Polynkin, A., Peyghambarian, N., Panasenko, D., Moloney, J. V., & Mansuripur, M. (2006). All-fiber source of high-power picosecond pulses at 1.5μm using short heavily-doped phosphate-fiber amplifier. In 2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 1-2.
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  We report using short, heavily-doped active phosphate fiber for generation of picosecond pulses at 1.5 mum, with the peak power of 19 kW which results in a record-high aerial power density of 24 GW/cm2 in the fiber core.
• Fallahi, M., Zakharian, A. R., Rathnakumar, R., Moloney, J. V., Mansuripur, M., Liu, T., & Fallahi, M. (2004). Applications of photonic crystals in optical data storage. In Optical Data Storage 2004, 5380, 430-438.
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  We propose the general idea of constructing an ultra-compact optical pickup based on photonic crystals. A few optical components necessary for various functions of an optical head are designed and analyzed.

Presentations

• Mansuripur, M. (2017, October). Mechanical Effects of Light: Radiation Pressure, Photon Momentum, and the Lorentz Force Law. University of Ottawa’s Weekly Colloquium Series. Ottawa, Canada: University of Ottawa.
• Mansuripur, M. (2018, January). Thermodynamics of Radiation Pressure and Photon Momentum (Part 2). SPIE Photonics West Symposium. San Francisco, California: SPIE.
• Mansuripur, M. (2017, August). Angular Momentum Exchange Between Light and Small Particles. SPIE Optics & Photonics Symposium. San Diego, California: SPIE.
• Mansuripur, M. (2017, August). Nature of the electromagnetic force between classical magnetic dipoles. SPIE Optics & Photonics Symposium. San diego, California: SPIE.
• Mansuripur, M. (2017, August). Thermodynamics of Radiation Pressure and Photon Momentum. SPIE Optics & Photonics Symposium. San Diego, California: SPIE.
• Mansuripur, M. (2017, July). Optical Angular Momentum in Classical Electrodynamics. 11th Asia-Pacific Conference on Near-field Optics (APNFO). Tainan, Taiwan: Asia-Pacific Conference on Near-field Optics.
• Mansuripur, M. (2017, July). Thermodynamics of Radiation Pressure and Photon Momentum. Seminar at Academia Sinica, Taipei (Taiwan). Taipei (Taiwan): Academia Sinica.
• Mansuripur, M. (2017, May). Field Momentum and Structured Light. Workshop on Quantum Field Framework for Structured Light Interactions, Banff International Research Station (BIRS). Banff International Research Station (Canada): Banff International Research Station.
• Mansuripur, M. (2017, November). Principles of Macromolecular Data Storage. University of New Mexico’s Weekly Colloquium Series. University of New Mexico, Albuquerque, New Mexico: University of New Mexico.
• Mansuripur, M. (2017, November). Thermodynamics of radiation pressure and photon momentum. Faculty Research Seminar, University of New Mexico, Albuquerque, New Mexico. University of New Mexico, Albuquerque, New Mexico: University of New Mexico.
• Mansuripur, M. (2017, October). Thermodynamics of radiation pressure and photon momentum. Faculty Research Seminar, University of Ottawa. University of Ottawa, Canada: University of Ottawa.
• Mansuripur, M. (2016, August). Electromagnetic angular momentum in cylindrically-symmetric and spherically-symmetric systems. SPIE Optics & Photonics Symposium. San Diego, California.
• Mansuripur, M. (2016, August). Momentum exchange between photons and phonons in structured media. SPIE Optics & Photonics Symposium. San Diego, California.
• Mansuripur, M. (2016, February). Light-matter interaction: Conversion of optical energy and momentum to mechanical vibrations and phonons. SPIE Photonics West Symposium.
• Mansuripur, M. (2016, January). Principles of Macromolecular Data Storage. Department of Management Information Systems, University of Arizona. Tucson, Arizona.
• Mansuripur, M., Kolesik, M., & Jakobsen, P. (2016, August). Spin and orbital angular momenta of trapped electromagnetic fields in leaky optical cavities. SPIE Optics & Photonics Symposium. San Diego, California.
• Zhu, Z., Mankowski, T., Balakrishnan, K., Shikoh, A. S., Touati, F., Benammar, M. A., Mansuripur, M., & Falco, C. M. (2016, August). A new hybrid transparent conductive electrode based on copper nanowires and its application in solar cells. SPIE Optics & Photonics Symposium. San Diego, California.
• Mansuripur, M. (2015, August). Advances in Macromolecular Data Storage. Biophotonics Symposium, SPIE Annual Meeting. San Diego, California.
• Mansuripur, M. (2015, August). Energy and Linear and Angular Momenta in Simple Electromagnetic Systems. SPIE Annual Meeting. San Diego, California.
• Mansuripur, M. (2015, August). Fabrication of aluminum-doped zinc oxide transparent conductive electrodes using plasma treatment for solar cell applications. SPIE Annual Meeting. San Diego, California.
• Mansuripur, M. (2015, August). Origin of the Spin-Orbit Interaction. SPIE Annual Meeting. San Diego , California.
• Mansuripur, M. (2015, August). Simple explanation of opto-mechanical cooling by the back action of cavity photons. SPIE Annual Meeting. San Diego, California.
• Mansuripur, M. (2015, February). Electric and Magnetic Dipoles in the Lorentz and Einstein-Laub Formulations of Classical Electrodynamics. SPIE Photonics West. San Francisco, California: SPIE -- The International Society for Optics & Photonics.
• Mansuripur, M. (2015, November). How CD and DVD Players Work. Qatar University. Doha, Qatar.
• Mansuripur, M. (2015, October). Advances in Macromolecular Data Storage. International Symposium on Optical Memory (ISOM). Toyama, Japan.
• Mansuripur, M. (2015, October). Advances in Macromolecular Data Storage. Jinan University. Guangzhou, People’s Republic of China.
• Mansuripur, M. (2015, October). How CD and DVD Players Work. Jinan University. Guangzhou, People’s Republic of China.
• Mansuripur, M. (2015, September). Principles of Macromolecular Data Storage. IBM Research & Development Group. Tucson, Arizona.
• Mankowski, T. S., Zhu, Z., Balakrishnan, K., Shikoh, A. S., Touati, F., Benammar, M. A., Mansuripur, M., & Falco, C. M. (2014, August). Metal nanowire-graphene composite transparent electrodes. SPIE Annual Meeting. San Diego, California: SPIE.
• Mansuripur, M. (2014, August). Advances in Macromolecular Data Storage. SPIE Symposium on Optical Data Storage. San Diego, California: SPIE.
• Mansuripur, M. (2014, August). Electromagnetic force and torque in Lorentz and Einstein-Laub formulations. Optical Trapping and Optical Micromanipulation XI, SPIE Annual Meeting. San Diego, California: SPIE -- International Society for Optics and Photonics.
• Mansuripur, M. (2014, August). Mechanical effects of light on material media: radiation pressure and the linear and angular momenta of photons. 50th Anniversary of the College of Optical Sciences, SPIE Annual Meeting. San Diego, California.
• Mansuripur, M. (2014, August). On the Electrodynamics of Moving Permanent Dipoles in External Electromagnetic Fields. Metamaterials Conference, SPIE Annual Meeting. San Diego, California: SPIE.
• Mansuripur, M. (2014, August). The Charge-Magnet Paradoxes of Classical Electrodynamics. Spintronics VII, SPIE Annual Meeting. San Diego, California: SPIE -- International Society for Optics and Photonics.
• Mansuripur, M. (2014, November). Advances in Macromolecular Data Storage. Seminar in the School of Mathematical & Statistical Sciences, Arizona State University. Tempe, Arizona: School of Mathematical & Statistical Sciences, Arizona State University.
• Mansuripur, M. (2014, November). Mechanical Effects of Light on Material Media: Radiation Pressure and the Linear and Angular Momenta of Photons. Seminar in the School of Mathematical & Statistical Sciences, Arizona State University. Tempe, Arizona: School of Mathematical & Statistical Sciences, Arizona State University.
• Mansuripur, M. (2014, October). Advances in Macromolecular Data Storage. Seminar in the College of Engineering, Qatar University. Doha, Qatar: College of Engineering, Qatar University.
• Mansuripur, M. (2014, October). Mechanical Effects of Light: Radiation Pressure, Photon Momentum, and the Lorentz Force Law. Weekly Colloquium Series, College of Optical Sciences, University of Arizona. Tucson: College of Optical Sciences, University of Arizona.
• Mansuripur, M. (2014, October). Mechanical Effects of Light: Radiation Pressure, Photon Momentum, and the Lorentz Force Law. Weekly Colloquium Series, Department of Physics, San Jose State University. San Jose, California: Department of Physics, San Jose State University.
• Mansuripur, M. (2014, October). The Force Law of Classical Electrodynamics: Lorentz versus Einstein and Laub. Symposium on the 50th Anniversary of the College of Optical Sciences, OSA Annual Meeting. Tucson: Optical Society of America (OSA).
• Mansuripur, M. (2014, September). Mechanical Effects of Light: Radiation Pressure, Photon Momentum, and the Lorentz Force Law. 2nd International Conference and Exhibition on Lasers, Optics & Photonics. Philadelphia, Pennsylvania: International Conference & Exhibition on Lasers, Optics & Photonics.
• Mansuripur, M. (2014, September). Mechanical Effects of Light: Radiation Pressure, Photon Momentum, and the Lorentz Force Law. Seminar, College of Engineering, University of Pennsylvania. Philadelphia, Pennsylvania: University of Pennsylvania.
• Zhu, Z., Mankowski, T. S., Balakrishnan, K., Shikoh, A. S., Touati, F., Benammar, M. A., Mansuripur, M., & Falco, C. M. (2014, August). Transparent conducting electrodes based on thin, ultra-long copper nanowires and graphene nano-composites. SPIE Annual Meeting. San Diego, California: SPIE.