Khanh Q Kieu

Interests

No activities entered.

Courses

Scholarly Contributions

Journals/Publications

• Banerjee, B., Kieu, K. Q., Vagner, J., Matsunaga, T. O., McDaniel, A., & Cromey, B. (2018). Pancreatic cancer cell detection by targeted lipid microbubbles and multiphoton imaging. Journal of Biomedical Optics, 23(4), 1-8.
• Churin, D., Olson, J., Norwood, R. A., Peyghambarian, N., & Kieu, K. (2015). High power synchronously pumped femtosecond Raman fiber laser. 2015 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO).
• Churin, D., Olson, J., Norwood, R. A., Peyghambarian, N., & Kieu, K. (2015). High-power synchronously pumped femtosecond Raman fiber laser. OPTICS LETTERS, 40(11), 2529-2532.
• Cocilovo, B., Herrera, O. D., Mehravar, S., Fang, Y., Sandhage, K. H., Kieu, K., & Norwood, R. A. (2015). Surface-Enhanced Two-Photon Excitation Fluorescence of Various Fluorophores Evaluated Using a Multiphoton Microscope. JOURNAL OF LIGHTWAVE TECHNOLOGY, 33(16), 3446-3452.
• Cohoon, G. A., Alvarez, C. E., Meyers, K., Deheyn, D. D., Hildebrand, M., Kieu, K., & Norwood, R. A. (2015). Analysis of quasi-periodic pore-network structure of centric marine diatom frustules. BIOINSPIRED BIOINTEGRATED BIOENGINEERED PHOTONIC DEVICES III, 9341.
• Gowda, R., Nguyen, N., Diels, J. -., Norwood, R. A., Peyghambarian, N., & Kieu, K. (2015). All-fiber bidirectional optical parametric oscillator for precision sensing. OPTICS LETTERS, 40(9), 2033-2036.
• Gowda, R., Nguyen, N., Diels, J., Norwood, R., Peyghambarian, N., & Kieu, K. (2015). All-fiber bidirectional optical parametric oscillator for precision rotation sensing. 2015 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO).
• Karvonen, L., Saynatjoki, A., Mehravar, S., Rodriguez, R. D., Hartmann, S., Zahn, D., Honkanen, S., Norwood, R. A., Peyghambarian, N., Kieu, K., Lipsanen, H., & Riikonen, J. (2015). Investigation of Second- and Third-Harmonic Generation in Few-Layer Gallium Selenide by Multiphoton Microscopy. SCIENTIFIC REPORTS, 5.
• Lynn, B., Miles, A., Mehravar, S., Blanche, P., Kieu, K., Norwood, R. A., & Peyghambarian, N. (2015). Real-time imaging of chromophore alignment in photorefractive polymer devices through multiphoton microscopy. MRS COMMUNICATIONS, 5(2), 243-250.
• Milster, T. D., Lu, P., & Kieu, K. (2015). Potential of multi-photon reading and writing for optical data storage systems. OPTICAL DATA STORAGE 2015, 9587.
• Puckett, M. W., Sharma, R., Vallini, F., Shahin, S., Monifi, F., Barrina, P. N., Mehravar, S., Kieu, K., & Fainman, Y. (2015). Silicon nanoridge array waveguides for nonlinear and sensing applications. OPTICS EXPRESS, 23(22), 28224-28233.
• Churin, D., Kieu, K., Norwood, R. A., & Peyghambarian, N. (2014). Efficient Frequency Comb Generation in the 9-mu m Region Using Compact Fiber Sources. IEEE PHOTONICS TECHNOLOGY LETTERS, 26(22), 2271-2274.
  More info

  We demonstrate a midinfrared (mid-IR) frequency comb spanning from 7.5 to 11.6 mu m at a -20-dB level using difference frequency generation in a AgGaS2 crystal with a compact all-fiber source based on Tm3+ and Er3+-amplifiers. The power of the mid-IR signal is measured to be 1.55 mW and the photon conversion efficiency is 16%. The pulse duration achieved in the mid-IR range is estimated to be similar to 80 fs, which corresponds to 2.6 optical cycles at the 9.2-mu m center wavelength. The current approach allows simple power scaling by further amplification of the pump and signal pulses using established fiber amplifier technologies.
• Cohoon, G. A., Kieu, K., & Norwood, R. A. (2014). Multiphoton excitation of organic chromophores in microbubble resonators. Proceedings of SPIE - The International Society for Optical Engineering, 8960.
  More info

  Abstract: We report the observation of multiphoton excitation of organic chromophores in microbubble whispering gallery mode resonators. High-Q microbubble resonators are a formed by heating a pressurized fused silica capillary to form a hollow bubble which can be filled with liquid. In this case, the microbubble is filled with a solution of Rhodamine 6G dye. The resonator and dye are excited by evanescently coupling CW light from a 980nm laser diode using a tapered optical fiber. The two-photon fluorescence of the dye can be seen with pump powers as low as 1 mW. © 2014 SPIE.
• Freudiger, C. W., Yang, W., Holtom, G. R., Peyghambarian, N., Xie, X. S., & Kieu, K. Q. (2014). Stimulated Raman scattering microscopy with a robust fibre laser source. Nature Photonics, 8(2), 153-159.
  More info

  Abstract: Stimulated Raman scattering microscopy allows label-free chemical imaging and has enabled exciting applications in biology, material science and medicine. It provides a major advantage in imaging speed over spontaneous Raman scattering and has improved image contrast and spectral fidelity compared to coherent anti-Stokes Raman scattering. Wider adoption of the technique has, however, been hindered by the need for a costly and environmentally sensitive tunable ultrafast dual-wavelength source. We present the development of an optimized all-fibre laser system based on the optical synchronization of two picosecond power amplifiers. To circumvent the high-frequency laser noise intrinsic to amplified fibre lasers, we have further developed a high-speed noise cancellation system based on voltage-subtraction autobalanced detection. We demonstrate uncompromised imaging performance of our fibre-laser-based stimulated Raman scattering microscope with shot-noise-limited sensitivity and an imaging speed up to 1 frame s -1. © 2014 Macmillan Publishers Limited.
• Herrera, O. D., Schneebeli, L., Kieu, K., Norwood, R. A., & Peyghambarian, N. (2014). Raman-induced frequency shift in CS2-filled integrated liquid-core optical fiber. OPTICS COMMUNICATIONS, 318, 83-87.
  More info

  We demonstrate an optically tunable frequency shift in an all-fiber based system using a carbon disulfide (CS2) filled integrated liquid-core optical fiber (i-LCOF) and co-propagating pulses of comparable temporal lengths. In 1 m of i-LCOF we were able to shift 18 ps pulses, a full spectral bandwidth at low pump peak powers, using the Raman-induced frequency shift and slow light effects. Numerical simulations of the pulse-propagation equations agree well with the observed shifts. We also analyze the contributions of both the Raman cross-frequency shift and slow light effects to the overall frequency shift. The system is all-fiber based and compact, making it suitable for applications such as a low power wavelength converter. (C) 2014 Elsevier B.V. All rights reserved.
• Kieu, K. Q. (2014). Characterization of coplanar poled electro optic polymer films for Si-photonic devices with multiphoton microscopy. APPLIED PHYSICS LETTERS, 104(16).
  More info

  We imaged coplanar poled electro optic (EO) polymer films on transparent substrates with a multiple-photon microscope in reflection and correlated the second-harmonic light intensity with the results of Pockels coefficient (r(33)) measurements. This allowed us to make quantitative measurements of poled polymer films on non-transparent substrates like silicon, which are not accessible with traditional Pockels coefficient measurement techniques. Phase modulators consisting of silicon waveguide devices with EO polymer claddings with a known Pockels coefficient (from V-pi measurements) were used to validate the correlation between the second-harmonic signal and r(33). This also allowed us to locally map the r(33) coefficient in the poled area.
• Kieu, K. Q. (2014). Multiphoton microscopy as a detection tool for photobleaching of EO materials. Optics Express, 22(25), 30955-30962.
  More info

  Multi-photon microscopy operating at 1550 nm is employed as a rapid characterization tool for studying the photostability of three well-known electro-optical materials. Different nonlinear optical responses such as multi-photon excitation fluoresence, second-, and third-harmonic generation can be used as detection probes to reveal the degradation mechanisms. This technique is rapid, accurate, and can be used to study the photostability of a broad range of materials.
• Kieu, K. Q. (2014). Observation of two-photon fluorescence for Rhodamine 6G in microbubble resonators. Optics Letters, 39(11), 3098-3101.
  More info

  We report an observation of multi-photon excitation of organic chromophores in microbubble whispering gallery mode resonators. High-Q microbubble resonators were formed by heating a pressurized fused silica capillary to form a hollow bubble that was then filled with liquid. In this work, the microbubble was filled with a solution of Rhodamine 6G dye. The resonator and dye were excited by evanescently coupling continuous wave (CW) light from a 980 nm laser diode using a tapered optical fiber. The two-photon fluorescence of the dye can be seen with pump powers as low as 700 mu W.
• Kieu, K. Q. (2014). Third-order nonlinear optical characterization of organic chromophores using liquid-core optical fibers. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, 31(10), 2455-2459.
  More info

  We present our technique to characterize the third-order nonlinear optical properties of organic dyes in our previously introduced integrated liquid-core optical fiber (i-LCOF) platform. i-LCOF is filled with the solution of the organic dyes, and the change in the laser pulse spectral width due to self-phase modulation is investigated. The measurements are done at 1550 nm using a mode-locked femtosecond fiber laser. The solution/laser interaction length is long (similar to 50 cm), which removes the need for high-power pump pulses. This method is fast, simple, and can be extended to the characterization of other nanoscale particles such as quantum dots and plasmonic metal nanoparticles in solutions.
• Kieu, K. Q. (2014). Two-Photon Absorption in CdSe Colloidal Quantum Dots Compared to Organic Molecules. ACS Nano, 8(12), 12572-12586.
  More info

  We discuss fundamental differences in electronic structure as reflected in one- and two-photon absorption spectra of semiconductor quantum dots and organic molecules by performing systematic experimental and theoretical studies of the size-dependent spectra of colloidal quantum dots. Quantum-chemical and effective-mass calculations are used to model the one- and two-photon absorption spectra and compare them with the experimental results. Currently, quantum-chemical calculations are limited to only small-sized quantum dots (nanoclusters) but allow one to study various environmental effects on the optical spectra such as solvation and various surface functionalizations. The effective-mass calculations, on the other hand, are applicable to the larger-sized quantum dots and can, in general, explain the observed trends but are insensitive to solvent and ligand effects. Careful comparison of the experimental and theoretical results allows for quantifying the range of applicability of theoretical methods used in this work. Our study shows that the small clusters can be in principle described in a manner similar to that used for organic molecules. In addition, there are several important factors (quality of passivation, nature of the ligands, and intraband/interband transitions) affecting optical properties of the nanoclusters. The larger-size quantum dots, on the other hand, behave similarly to bulk semiconductors, and can be well described in terms of the effective-mass models.
• Kieu, K., Li, C., Fang, Y., Cohoon, G., Herrera, O. D., Hildebrand, M., Sandhage, K. H., & Norwood, R. A. (2014). Structure-based optical filtering by the silica microshell of the centric marine diatom Coscinodiscus wailesii. OPTICS EXPRESS, 22(13), 15992-15999.
  More info

  Diatoms are a renewable (biologically reproducible) source of three-dimensional (3-D) nanostructured silica that could be attractive for a variety of photonic devices, owing to the wide range of quasi-periodic patterns of nano-to-microscale pores available on the silica microshells (frustules) of various diatom species. We have investigated the optical behavior of the silica frustule of a centric marine diatom, Coscinodiscus wailesii, using a coherent broadband (400-1700 nm) supercontinuum laser focused to a fine (20 mu m diameter) spot. The C. wailesii frustule valve, which possessed a quasi-periodic hexagonal pore array, exhibited position-dependent optical diffraction. Changes in such diffraction behavior across the frustule were consistent with observed variations in the quasi-periodic pore pattern. (C)2014 Optical Society of America
• Alasaarela, T., Karvonen, L., Jussila, H., Säynätjoki, A., Mehravar, S., Norwood, R. A., Peyghambarian, N., Kieu, K., Tittonen, I., & Lipsanen, H. (2013). High-quality crystallinity controlled ALD TiO₂ for waveguiding applications. Optics Letters, 38(20), 3980-3983.
  More info

  PMID: 24321899;Abstract: We demonstrate a novel atomic layer deposition (ALD) process to make high-quality nanocrystalline titanium dioxide (TiO2) with intermediate Al2O3 layers to limit the crystal size. The process is based on titanium chloride (TiCl4) + water and trimethyl aluminum (TMA) + ozone processes at 250°C deposition temperature. The waveguide losses measured using a prism coupling method for 633 and 1551 nm wavelengths are as low as 0.2 ± 0.1 dB/mm with the smallest crystal size, with losses increasing with crystal size. In comparison, plain TiO2 deposited at 250°C without the intermediate Al2O3 layers shows high scattering losses and is not viable as waveguide material. The third-order optical nonlinearity decreases with smaller crystal size as verified by third-harmonic generation microscopy but still remains high for all samples. Crystallinity controlled ALD-grown TiO2 is an excellent candidate for various optical applications, where good thermal stability and high third-order optical nonlinearity are needed. © 2013 Optical Society of America.
• Churin, D., Nguyen, T. N., Kieu, K., Norwood, R. A., & Peyghambarian, N. (2013). Mid-IR supercontinuum generation in an integrated liquid-core optical fiber filled with CS2. OPTICAL MATERIALS EXPRESS, 3(9), 1358-1364.
  More info

  We report supercontinuum generation in a 16cm long integrated liquid-core optical fiber (LCOF) filled with neat carbon disulfide (CS2). The LCOF was pumped with compact mode-locked fiber lasers operating near 1560nm and 1910nm. The supercontinuum spanned from 1460nm to 2100nm and from 1790nm to 2400nm at 20 dB level for 1560nm and 1910nm pump wavelengths, respectively. The spectral broadening extended mostly to longer wavelengths due to the high Raman contribution to the nonlinear optical response of CS2. The experimental results are in good agreement with numerical simulations. (c) 2013 Optical Society of America
• Churin, D., Nguyen, T. N., Kieu, K., Norwood, R. A., & Peyghambarian, N. (2013). Mid-IR supercontinuum generation in an integrated liquid-core optical fiber filled with CS₂. Optical Materials Express, 3(9), 1358-1364.
  More info

  Abstract: We report supercontinuum generation in a 16cm long integrated liquid-core optical fiber (LCOF) filled with neat carbon disulfide (CS2). The LCOF was pumped with compact mode-locked fiber lasers operating near 1560nm and 1910nm. The supercontinuum spanned from 1460nm to 2100nm and from 1790nm to 2400nm at 20 dB level for 1560nm and 1910nm pump wavelengths, respectively. The spectral broadening extended mostly to longer wavelengths due to the high Raman contribution to the nonlinear optical response of CS2. The experimental results are in good agreement with numerical simulations. © 2013 Optical Society of America.
• Fang, Q., Shi, W., Petersen, E., Kieu, K., Chavez-Pirson, A., & Peyghambarian, N. (2013). Half-mJ All-Fiber-Based Single-Frequency Nanosecond Pulsed Fiber Laser at 2-mu m. IEEE PHOTONICS TECHNOLOGY LETTERS, 24(5), 353-355.
  More info

  We report a high energy, high peak power, all-fiber-based single-frequency similar to 15-ns pulsed laser source at similar to 1918.4 nm in master oscillator-power amplifier configuration. The pulsed fiber laser seed was achieved by directly modulating a continuous-wave single-frequency fiber laser using an electro-optic modulator driven by an arbitrary waveform generator to pre-shape the pulses before amplification to mitigate pulse steepening and dynamic gain saturation. One piece of large (25-mu m) core, polarization-maintaining highly thulium-doped germanate glass fiber was used in the power amplifier stage to boost the energy and the peak power of the 15-ns pulses to >0.5 mJ and >33 kW without any nonlinearities.
• Herrera, O. D., Schneebeli, L., Kieu, K., Norwood, R. A., & Peyghambarian, N. (2013). Slow light based on stimulated Raman scattering in an integrated liquid-core optical fiber filled with CS2. OPTICS EXPRESS, 21(7), 8821-8830.
  More info

  We demonstrate a fiber-based slow light system using a carbon disulfide (CS2) filled integrated liquid-core optical fiber (i-LCOF). Using 1 meter of i-LCOF we were able to delay 18ps pulses up to 34ps; a delay of 188% of the pulse width. This experimental setup serves as a foundation for slow-light experiments in other nonlinear liquids. Numerical simulations of pulse-propagation equations confirmed the observed delay and a simplified method is presented that can be applied to calculate induced delay for non-cw Stokes pulses. The system is all-fiber and compact with delays greater than a pulse width, indicating potential application as an ultrafast controllable delay line for time division multiplexing in multiGb/s telecommunication systems. (c) 2013 Optical Society of America
• Herrera, O. D., Schneebeli, L., Kieu, K., Norwood, R. A., & Peyghambarian, N. (2013). Slow light based on stimulated Raman scattering in an integrated liquid-core optical fiber filled with CS₂. Optics Express, 21(7), 8821-8830.
  More info

  PMID: 23571972;Abstract: We demonstrate a fiber-based slow light system using a carbon disulfide (CS2) filled integrated liquid-core optical fiber (i-LCOF). Using 1 meter of i-LCOF we were able to delay 18ps pulses up to 34ps; a delay of 188% of the pulse width. This experimental setup serves as a foundation for slow-light experiments in other nonlinear liquids. Numerical simulations of pulse-propagation equations confirmed the observed delay and a simplified method is presented that can be applied to calculate induced delay for noncw Stokes pulses. The system is all-fiber and compact with delays greater than a pulse width, indicating potential application as an ultrafast controllable delay line for time division multiplexing in multiGb/s telecommunication systems. © 2013 Optical Society of America.
• Himmelhuber, R., Kieu, K., Herrera, O. D., Norwood, R. A., & Peyghambarian, N. (2013). Characterization of coplanar poled electro optic polymer films for Si-photonic devices with multiphoton microscopy. 2013 Optical Interconnects Conference, OI 2013, 90-91.
  More info

  Abstract: 1. Introduction Electro-optic (EO) polymers are of great as interest as they have been successfully used in EO modulators showing sub-volt Vn [1], low optical loss [2] and operating bandwidths above 100GHz [3]. © 2013 IEEE.
• Karvonen, L., Säynätjoki, A., Chen, Y., Jussila, H., Rönn, J., Ruoho, M., Alasaarela, T., Kujala, S., Norwood, R. A., Peyghambarian, N., Kieu, K., & Honkanen, S. (2013). Enhancement of the third-order optical nonlinearity in ZnO/Al ₂O₃ nanolaminates fabricated by atomic layer deposition. Applied Physics Letters, 103(3).
  More info

  Abstract: We investigate the third-order optical nonlinearity in ZnO/Al 2O3 nanolaminates fabricated by atomic layer deposition and show that the third-order optical nonlinearity can be enhanced by nanoscale engineering of the thin film structure. The grain size of the polycrystalline ZnO film is controlled by varying the thickness of the ZnO layers in the nanolaminate in which thin (∼2 nm) amorphous Al2O3 layers work as stopping layers for ZnO crystal growth. Nanoscale engineering enables us to achieve a third harmonic generated signal enhancement of ∼13 times from the optimized nanolaminate structure compared to a ZnO reference film of comparable thickness. © 2013 AIP Publishing LLC.
• Kieu, K., Churin, D., Schneebeli, L., Norwood, R. A., & Peyghambarian, N. (2013). Brillouin lasing in integrated liquid-core optical fibers. Optics Letters, 38(4), 543-545.
  More info

  PMID: 23455130;Abstract: We report Brillouin lasing in an integrated liquid-core optical fiber filled with neat CS2. This is the first observation of Brillouin lasing in an optical fiber filled with a liquid, to the best of our knowledge. The linewidth of the single frequency liquid-based Brillouin laser was estimated to be
• Kieu, K., Mehravar, S., Gowda, R., Norwood, R. A., & Peyghambarian, N. (2013). Label-free multi-photon imaging using a compact femtosecond fiber laser mode-locked by carbon nanotube saturable absorber. Biomedical Optics Express, 4(10), 2187-2195.
  More info

  PMID: 24156074;PMCID: PMC3799676;Abstract: We demonstrate label-free multi-photon imaging of biological samples using a compact Er3+-doped femtosecond fiber laser mode-locked by a single-walled carbon nanotube (CNT). These compact and low cost lasers have been developed by various groups but they have not been exploited for multiphoton microscopy. Here, it is shown that various multiphoton imaging modalities (e.g. second harmonic generation (SHG), third harmonic generation (THG), two-photon excitation fluorescence (TPEF), and three-photon excitation fluorescence (3PEF)) can be effectively performed on various biological samples using a compact handheld CNT mode-locked femtosecond fiber laser operating in the telecommunication window near 1560nm. We also show for the first time that chlorophyll fluorescence in plant leaves and diatoms can be observed using 1560nm laser excitation via three-photon absorption. © 2013 Optical Society of America.
• Kieu, K., Schneebeli, L., Hales, J. M., Perry, J. W., Norwood, R. A., & Peyghambarian, N. (2013). Demonstration of Zeno switching through inverse Raman scattering in an optical fiber. OPTICS EXPRESS, 19(13), 12532-12539.
  More info

  We report the observation of Zeno switching through an inverse Raman scattering (IRS) process in an optical fiber. In IRS, light at the anti-Stokes frequency is strongly attenuated in the presence of a pump field, allowing it to be used for all-optical switching and modulation. Our observed level of induced absorption via IRS in the optical fiber is > 20dB in a time scale of less than 5 ps. The full Raman response spectrum was extracted experimentally and excellent agreement was found between the experimental data and theoretical modeling of IRS. (C)2011 Optical Society of America
• Kim, C., Bae, S., Kieu, K., & Kim, J. (2013). Sub-femtosecond timing jitter, all-fiber, CNT-mode-locked Er-laser at telecom wavelength. OPTICS EXPRESS, 21(22), 26533-26541.
  More info

  We demonstrate a 490-attosecond timing jitter (integration bandwidth: 10 kHz - 39.4 MHz) optical pulse train from a 78.7-MHz repetition rate, all-fiber soliton Er laser mode-locked by a fiber tapered carbon nanotube saturable absorber (ft-CNT-SA). To achieve this jitter performance, we searched for a net cavity dispersion condition where the Gordon-Haus jitter is minimized while maintaining stable soliton mode-locking. Our result shows that optical pulse trains with well below a femtosecond timing jitter can be generated from a self-starting and robust all-fiber laser operating at telecom wavelength. (C) 2013 Optical Society of America
• Kim, C., Bae, S., Kieu, K., & Kim, J. (2013). Sub-femtosecond timing jitter, all-fiber, CNTmode-locked Er-laser at telecom wavelength. Optics Express, 21(22), 26533-26541.
  More info

  PMID: 24216875;Abstract: We demonstrate a 490-attosecond timing jitter (integration bandwidth: 10 kHz - 39.4 MHz) optical pulse train from a 78.7-MHz repetition rate, all-fiber soliton Er laser mode-locked by a fiber tapered carbon nanotube saturable absorber (ft-CNT-SA). To achieve this jitter performance, we searched for a net cavity dispersion condition where the Gordon-Haus jitter is minimized while maintaining stable soliton modelocking. Our result shows that optical pulse trains with well below a femtosecond timing jitter can be generated from a self-starting and robust all-fiber laser operating at telecom wavelength. ©2013 Optical Society of America.
• Kim, Y., Phat, L. u., Milster, T. D., & Kieu, K. (2013). Hyper-numerical aperture (NA = 2.8) microscope using λ = 1.56 μm femtosecond source for multi-photon imaging. Biomedical Optics Express, 4(10), 1786-1794.
  More info

  PMID: 24156043;PMCID: PMC3799645;Abstract: A new microscope is discussed, where the scanning illumination has a numerical aperture of 2.8 with λ = 1.56 μm femtosecond fiber laser. Samples are placed or grown on a silicon substrate. Multi-photon emission is imaged in transmission on a cooled CCD. Two-photon and three-photon effects are observed from the silicon/water interface and gold nanoparticles. Images of cells, reference spheres and gold nanoparticles illustrate imaging properties of the microscope. Spectral characteristics of individual particles are achieved with a blazed transmission grating. Emission properties of differently sized gold nanoparticles are studied in detail, which indicate that their emission is a two-photon effect due continuum generation. Interestingly, spectral shape and emission power are similar for 20nm, 40nm and 60nm diameter gold nanoparticles for the cases studied. © 2013 Optical Society of America.
• Nguyen, T. N., Kieu, K., Churin, D., Ota, T., Miyawaki, M., & Peyghambarian, N. (2013). High power soliton self-frequency shift with improved flatness ranging from 1.6 to 1.78. IEEE Photonics Technology Letters, 25(19), 1893-1896.
  More info

  Abstract: We report on the demonstration of a high power tunable femtosecond fiber laser based on soliton self-frequency shift in a large mode area photonic crystal fiber. The laser provides up to 13 nJ pulse energy, ∼550 mW average power, and wavelength tuning range from 1600 to 1780 nm. The pulse duration is sub-100 fs over the entire tuning range. We have also demonstrated a novel way of tuning the laser output wavelength using chirp control which has allowed us to achieve higher average output power within the tuning range. We believe the laser system will be useful for high speed deep tissue multiphoton bio-imaging and difference frequency generation to create high power tunable mid-IR radiation. © 2013 IEEE.
• Nguyen, T. N., Kieu, K., Maslov, A. V., Miyawaki, M., & Peyghambarian, N. (2013). Normal dispersion femtosecond fiber optical parametric oscillator. Optics Letters, 38(18), 3616-3619.
  More info

  PMID: 24104828;Abstract: We propose and demonstrate a synchronously pumped fiber optical parametric oscillator (FOPO) operating in the normal dispersion regime. The FOPO generates chirped pulses at the output, allowing significant pulse energy scaling potential without pulse breaking. The output average power of the FOPO at 1600 nm was ∼60 mW (corresponding to 1.45 nJ pulse energy and ∼55% slope power conversion efficiency). The output pulses directly from the FOPO were highly chirped (∼3 ps duration), and they could be compressed outside of the cavity to 180 fs by using a standard optical fiber compressor. Detailed numerical simulation was also performed to understand the pulse evolution dynamics around the laser cavity. We believe that the proposed design concept is useful for scaling up the pulse energy in the FOPO using different pumping wavelengths. © 2013 Optical Society of America.
• Richards, B. C., Hendrickson, J., Olitzky, J. D., Gibson, R., Gehl, M., Kieu, K., Polynkin, P., Khitrova, G., Gibbs, H. M., Khankhoje, U. K., Homyk, A., Scherer, A., Kim, J. -., & Lee, Y. -. (2013). Progress in growth, fabrication, and characterization of semiconductor photonic crystal nanocavities. PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 248(4), 892-896.
  More info

  We present the results of recent investigations into the fabrication and characterization of high-Q, small mode volume one-dimensional photonic crystal nanobeam cavities in Si and two-dimensional photonic crystal slab nanocavities in GaAs. The nanobeam cavity modes are investigated in transmission by means of a microfiber taper loop apparatus. The spectral transmission profile of the cavity modes is investigated as a function of input polarization into the fiber. The Q of the cavity for different positions and orientations of the fiber taper is investigated. The results are compared to measurements by resonant scattering. The slab nanocavities are investigated by means of quantum dot photoluminescence excitation spectroscopy. We present recent progress in growth and fabrication of such slab nanocavities. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
• Schneebeli, L., Kieu, K., Merzlyak, E., Hales, J. M., DeSimone, A., Perry, J. W., Norwood, R. A., & Peyghambarian, N. (2013). Measurement of the Raman gain coefficient via inverse Raman scattering. Journal of the Optical Society of America B: Optical Physics, 30(11), 2930-2939.
  More info

  Abstract: We report a new characterization technique of Raman gain materials through inverse Raman scattering (IRS). The technique is applied to silica glass optical fiber and several liquids in liquid-core optical fiber (LCOF). We obtain good quantitative agreement with a conventional technique that estimates the gain coefficient from steady-state Raman scattering measurements. Our results demonstrate that IRS is a viable tool to characterize new materials for ultralow-power nonlinear optics and all-optical switching. © 2013 Optical Society of America.
• Shahin, S., Kieu, K., Marder, S. R., Norwood, R. A., & Peyghambarian, N. (2013). Novel method on n₂ measurement of organic dyes. CLEO: Science and Innovations, CLEO_SI 2013, CW3B.7.
  More info

  Abstract: A novel technique is introduced to characterize the nonlinear properties of organic dyes in solution. This technique uses the integrated liquid core optical fiber (i-LCOF) platform and is based on the spectral broadening of laser pulses due to self phase modulation (SPM). © 2013 Optical Society of America.
• Shahin, S., Kieu, K., Marder, S. R., Norwood, R. A., & Peyghambarian, N. (2013). SPM spectral broadening compensation using organic dyes with negative n₂. 2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2013.
  More info

  Abstract: Spectral broadening caused by SPM degrades performance of light-wave, multichannel communication systems. We propose a novel method in LCOF to compensate the SPM spectral broadening in systems using different concentrations of negative n2 organic dyes. © 2013 OSA.
• Shahin, S., Kieu, K., Marder, S. R., Norwood, R. A., & Peyghambarian, N. (2013). SPM spectral broadening compensation using organic dyes with negative n₂. National Fiber Optic Engineers Conference, NFOEC 2013, JW2A.13.
  More info

  Abstract: Spectral broadening caused by SPM degrades performance of light-wave, multichannel communication systems. We propose a novel method in LCOF to compensate the SPM spectral broadening in systems using different concentrations of negative n2 organic dyes. © 2013 Optical Society of America.
• Shahin, S., Kieu, K., Marder, S. R., Norwood, R. A., & Peyghambarian, N. (2013). SPM spectral broadening compensation using organic dyes with negative n₂. Optical Fiber Communication Conference, OFC 2013, JW2A.13.
  More info

  Abstract: Spectral broadening caused by SPM degrades performance of light-wave, multichannel communication systems. We propose a novel method in LCOF to compensate the SPM spectral broadening in systems using different concentrations of negative n2 organic dyes. © 2013 OSA.
• Säynätjoki, A., Karvonen, L., Riikonen, J., Kim, W., Mehravar, S., Norwood, R. A., Peyghambarian, N., Lipsanen, H., & Kieu, K. (2013). Rapid large-area multiphoton microscopy for characterization of graphene. ACS Nano, 7(10), 8441-8446.
  More info

  PMID: 24025127;Abstract: Single and few-layer graphene was studied with simultaneous third-harmonic and multiphoton-absorption-excited fluorescence microscopy using a compact 1.55 μm mode-locked fiber laser source. Strong third-harmonic generation (THG) and multiphoton-absorption-excited fluorescence (MAEF) signals were observed with high contrast over the signal from the substrate. High contrast was also achieved between single-and bilayer graphene. The measurement is straightforward and very fast compared to typical Raman mapping, which is the conventional method for characterization of graphene. Multiphoton microscopy is also proved to be an extremely efficient method for detecting certain structural features in few-layer graphene. The accuracy and speed of multiphoton microscopy make it a very promising characterization technique for fundamental research as well as large-scale fabrication of graphene. To our knowledge, this is the first time simultaneous THG and MAEF microscopy has been utilized in the characterization of graphene. This is also the first THG microscopy study on graphene using the excitation wavelength of 1.55 μm, which is significant in telecommunications and signal processing. © 2013 American Chemical Society.
• Tada, K., Cohoon, G. A., Kieu, K., Mansuripur, M., & Norwood, R. A. (2013). Fabrication of High-Q Microresonators Using Femtosecond Laser Micromachining. IEEE PHOTONICS TECHNOLOGY LETTERS, 25(5), 430-433.
  More info

  We report a technique to fabricate whispering gallery mode microdisk resonators using femtosecond laser micromachining and a heat reflow process to improve the optical quality of the resonator. The fabricated resonators have suppressed higher order modes with a measured Q-factor as high as 7.2 x 10(6). The described fabrication process, which relies on material non-thermal laser ablation, offers the ability to fabricate microresonators using a wide variety of materials of nearly any dimensional size or shape.
• Tada, K., Cohoon, G. A., Kieu, K., Mansuripur, M., & Norwood, R. A. (2013). Fabrication of high-Q microresonators using femtosecond laser micromachining. IEEE Photonics Technology Letters, 25(5), 430-433.
  More info

  Abstract: We report a technique to fabricate whispering gallery mode microdisk resonators using femtosecond laser micromachining and a heat reflow process to improve the optical quality of the resonator. The fabricated resonators have suppressed higher order modes with a measured Q-factor as high as 7.2× 106. The described fabrication process, which relies on material non-thermal laser ablation, offers the ability to fabricate microresonators using a wide variety of materials of nearly any dimensional size or shape. © 2012 IEEE.
• Thanh Nam Nguyen, ., Khanh Kieu, ., Churin, D., Ota, T., Miyawaki, M., & Peyghambarian, N. (2013). High Power Soliton Self-Frequency Shift With Improved Flatness Ranging From 1.6 to 1.78 mu m. IEEE PHOTONICS TECHNOLOGY LETTERS, 25(19), 1893-1896.
  More info

  We report on the demonstration of a high power tunable femtosecond fiber laser based on soliton self-frequency shift in a large mode area photonic crystal fiber. The laser provides up to 13 nJ pulse energy, similar to 550 mW average power, and wavelength tuning range from 1600 to 1780 nm. The pulse duration is sub-100 fs over the entire tuning range. We have also demonstrated a novel way of tuning the laser output wavelength using chirp control which has allowed us to achieve higher average output power within the tuning range. We believe the laser system will be useful for high speed deep tissue multiphoton bio-imaging and difference frequency generation to create high power tunable mid-IR radiation.
• Wei, C., Zhu, X., Norwood, R. A., Kieu, K., & Peyghambarian, N. (2013). Picosecond passively mode-locked mid-infrared fiber laser. Proceedings of SPIE - The International Society for Optical Engineering, 8601.
  More info

  Abstract: Mode-locked mid-infrared (mid-IR) fiber lasers are of increasing interest due to their many potential applications in spectroscopic sensors, infrared countermeasures, laser surgery, and high-efficiency pump sources for nonlinear wavelength convertors. Er3+-doped ZBLAN (ZrF4-BaF 2-LaF3-AlF3-NaF) fiber lasers, which can emit mid-IR light at 2.65-2.9 μm through the transition from the upper energy level 4I11/2 to the lower laser level 4I 13/2, have attracted much attention because of their broad emission range, high optical efficiency, and the ready availability of diode pump lasers at the two absorption peaks of Er3+ ions (975 nm and 976 nm). In recent years, significant progress on high power Er3+- doped ZBLAN fiber lasers has been achieved and over 20 watt cw output at 2.8 μm has been demonstrated; however, there has been little progress on ultrafast mid-IR ZBLAN fiber lasers to date. We report a passively mode-locked Er3+- doped ZBLAN fiber laser in which a Fe2+:ZnSe crystal was used as the intracavity saturable absorber. Fe2+:ZnSe is an ideal material for mid-IR laser pulse generation because of its large saturable absorption cross-section and small saturation energy along with the excellent opto-mechanical (damage threshold ∼2 J/cm2) and physical characteristics of the crystalline ZnSe host. A 1.6 m double-clad 8 mol% Er 3+-doped ZBLAN fiber was used in our experiment. The fiber core has a diameter of 15 μm and a numerical aperture (NA) of 0.1. The inner circular cladding has a diameter of 125 μm and an NA of 0.5. Both continuous-wave and Q-switched mode-locking pulses at 2.8 μm were obtained. Continuous-wave mode locking operation with a pulse duration of 19 ps and an average power of 51 mW were achieved when a collimated beam traversed the Fe2+:ZnSe crystal. When the cavity was modified to provide a focused beam at the Fe 2+:ZnSe crystal, Q-switched mode-locked operation with a pulse duration of 60 ps and an average power of 4.6 mW was achieved. More powerful and narrower pulses are expected if the dispersion of the cavity can be properly managed. © 2013 Copyright SPIE.
• Zhu, X., Schuelzgen, A., Wei, H., Kieu, K., & Peyghambarian, N. (2013). White light Bessel-like beams generated by miniature all-fiber device. OPTICS EXPRESS, 19(12), 11365-11374.
  More info

  Micron-sized white light propagation invariant beams generated by a simple and compact fiber device are presented. The all-fiber device is fabricated by splicing a short piece of large-core multimode fiber onto a small-core single mode white light delivery fiber. Because this fiber device offers an inherent spatial coherence, nondiffracting white light beams can be created with a temporally incoherent broadband light source (a halogen bulb) and, most importantly, the surrounding fringes don't fade as the bandwidth of the light source increases because the underlying physics of this fiber device is different from that of the axicon. White light Bessel-like beams have been generated from multimode fibers with core diameters of 50 mu m, 105 mu m, and 200 mu m. The distance of nondiffracting propagation of the white light Bessel beam increases with increasing core size of the multimode fiber. Propagation characteristics of red, green, and blue individual beams are also presented. (C) 2011 Optical Society of America
• Churin, D., Kieu, K., & Peyghambarian, N. (2012). The role of the saturable absorber in a mode-locked fiber laser. Fiber Lasers and Applications, FILAS 2012.
  More info

  Abstract: We systematically investigated the role of the saturable absorber (SA) in a mode-locked fiber laser. © 2012 OSA.
• Churin, D., Kieu, K., & Peyghambarian, N. (2012). The role of the saturable absorber in a mode-locked fiber laser. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 8237.
  More info

  Abstract: We experimentally investigated the role of the saturable absorber (SA) in a mode-locked fiber laser. It is shown that the modulation depth of the SA significantly affects the pulse duration at the laser output for a given cavity design (mainly cavity dispersion and nonlinearity). © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
• Fang, Q., Kieu, K., Shi, W., Petersen, E., Chavez-Pirson, A., & Peyghambarian, N. (2012). High energy high peak power monolithic single frequency 2 μm nanosecond pulsed fiber laser system. Fiber Lasers and Applications, FILAS 2012.
  More info

  Abstract: We report an all-fiber single frequency ~15 ns pulsed laser source at ~1918.4 nm, whose energy and peak power was boosted to >0.5 mJ and >33 kW in master oscillator-power amplifier configuration. © 2010 Optical Society of America.
• Fang, Q., Shi, W., Kieu, K., Petersen, E., Chavez-Pirson, A., & Peyghambarian, N. (2012). High power and high energy monolithic single frequency 2 μm nanosecond pulsed fiber laser by using large core Tm-doped germanate fibers: Experiment and modeling. Optics Express, 20(15), 16410-16420.
  More info

  Abstract: We report a high power and high energy all-fiber-based single frequency nanosecond pulsed laser source at ∼1918.4 nm in master oscillator-power amplifier (MOPA) configuration. The pre-shaped pulsed fiber laser seed with a variable pulse duration and repetition rate were achieved by directly modulating a continuous wave (CW) single frequency fiber laser using a fast electro-optical modulator (EOM) driven by a arbitrary waveform generator (AWG). One piece of single mode, large (30 μm) core polarization-maintaining (PM) highly thulium-doped (Tm-doped) germanate glass fiber (LC-TGF) was used to boost the pulse power and pulse energy of these modulated pulses in the final power amplifier. To the best of our knowledge, the highest average power 16 W for single frequency transform-limited ∼2.0 ns pulses at 500 kHz was achieved, and the highest peak power 78.1 kW was achieved at 100 kHz. Furthermore, mJ pulse energy was achieved for ∼15 ns pulses at 1 kHz repetition rate. Theoretical modeling of the large-core highly Tm-doped germanate glass double-cladding fiber amplifier (LC-TG-DC-FA) is also present for 2 μm nanosecond pulse amplification. A good agreement between the theoretical and experimental results was achieved. The model was also utilized to investigate the dependence of the stored energy in the LC-TGF on the pump power, seed energy and repetition rate, which can be used to design and optimize the LC-TG-DC-FA to achieve higher pulse energy. ©2012 Optical Society of America.
• Fang, Q., Shi, W., Petersen, E., Kieu, K., Chavez-Pirson, A., & Peyghambarian, N. (2012). Half-mJ all-fiber-based single-frequency nanosecond pulsed fiber laser at 2-μm. IEEE Photonics Technology Letters, 24(5), 353-355.
  More info

  Abstract: We report a high energy, high peak power, all-fiber-based single-frequency ∼15-ns pulsed laser source at ∼1918.4 nm in master oscillator-power amplifier configuration. The pulsed fiber laser seed was achieved by directly modulating a continuouswave single-frequency fiber laser using an electro-optic modulator driven by an arbitrary waveform generator to pre-shape the pulses before amplification to mitigate pulse steepening and dynamic gain saturation. One piece of large (25-μm) core, polarization-maintaining highly thulium-doped germanate glass fiber was used in the power amplifier stage to boost the energy and the peak power of the 15-ns pulses to >0.5 mJ and >33 kW without any nonlinearities. © 2011 IEEE.
• Kieu, K., & Mansuripur, M. (2012). Active Q switching of a fiber laser with a microsphere resonator. OPTICS LETTERS, 31(24), 3568-3570.
  More info

  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 similar to 102 W, duration similar to 160 ns) at a low pump-power threshold (similar to 3 mW). (c) 2006 Optical Society of America.
• Kieu, K., Churin, D., Norwood, R. A., & Peyghambarian, N. (2012). Brillouin lasing in integrated liquid-core optical fibers. 2012 Conference on Lasers and Electro-Optics, CLEO 2012.
  More info

  Abstract: We report Brillouin lasing in an integrated liquid-core optical fiber (i-LCOF) filled with neat CS2. This is the first observation of Brillouin lasing in the liquid state of matter, to the best of our knowledge. The linewidth of the single frequency liquid-based Brillouin laser was estimated to be < 1kHz by beating two similar but independent lasers. © 2012 OSA.
• Kieu, K., Churin, D., Norwood, R. A., & Peyghambarian, N. (2012). Brillouin lasing in integrated liquid-core optical fibers. CLEO: Applications and Technology, CLEO_AT 2012, CTh5D.8.
  More info

  Abstract: We report Brillouin lasing in an integrated liquid-core optical fiber (i-LCOF) filled with neat CS2. This is the first observation of Brillouin lasing in the liquid state of matter, to the best of our knowledge. The linewidth of the single frequency liquid-based Brillouin laser was estimated to be < 1kHz by beating two similar but independent lasers. © 2012 Optical Society of America.
• Kieu, K., Jones, R. J., & Peyghambarian, N. (2012). Generation of Few-Cycle Pulses From an Amplified Carbon Nanotube Mode-Locked Fiber Laser System. IEEE PHOTONICS TECHNOLOGY LETTERS, 22(20), 1521-1523.
  More info

  We report a simple femtosecond fiber laser system based on a carbon nanotube saturable absorber that is capable of generating 14-fs pulses (containing less than four optical cycles) with optical spectrum extending from 1000 nm to around 1500 nm.
• Kieu, K., Mehravar, S., Gowda, R., Norwood, R. A., & Peyghambarian, N. (2012). Label-free multi-photon imaging using a compact femtosecond fiber laser mode-locked by carbon nanotube saturable absorber. BIOMEDICAL OPTICS EXPRESS, 4(10), 2187-2195.
  More info

  We demonstrate label-free multi-photon imaging of biological samples using a compact Er3+-doped femtosecond fiber laser mode-locked by a single-walled carbon nanotube (CNT). These compact and low cost lasers have been developed by various groups but they have not been exploited for multiphoton microscopy. Here, it is shown that various multiphoton imaging modalities (e.g. second harmonic generation (SHG), third harmonic generation (THG), two-photon excitation fluorescence (TPEF), and three-photon excitation fluorescence (3PEF)) can be effectively performed on various biological samples using a compact handheld CNT mode-locked femtosecond fiber laser operating in the telecommunication window near 1560nm. We also show for the first time that chlorophyll fluorescence in plant leaves and diatoms can be observed using 1560nm laser excitation via three-photon absorption. (C) 2013 Optical Society of America
• Kieu, K., Merzlyak, Y., Schneebeli, L., Hales, J., Perry, J., Norwood, R. A., & Peyghambarian, N. (2012). Integrated liquid-core optical fiber for nonlinear liquid photonics. Optics InfoBase Conference Papers.
  More info

  Abstract: We have developed a technique that allows splicing of liquid core optical fiber (LCOF) to standard single-mode optical fiber with low loss (
• Kieu, K., Merzlyak, Y., Schneebeli, L., Hales, J., Perry, J., Norwood, R. A., & Peyghambarian, N. (2012). Integrated liquid-core optical fibers for ultra-efficient nonlinear liquid photonics. 2012 Conference on Lasers and Electro-Optics, CLEO 2012.
  More info

  Abstract: We have developed a technique that allows splicing of liquid core optical fiber (LCOF) to standard fiber with low loss. As an example, we demonstrated ultralow threshold Raman generation in an integrated CS2 filled LCOF. © 2012 OSA.
• Kieu, K., Merzlyak, Y., Schneebeli, L., Hales, J., Perry, J., Norwood, R. A., & Peyghambarian, N. (2012). Integrated liquid-core optical fibers for ultra-efficient nonlinear liquid photonics. CLEO: Science and Innovations, CLEO_SI 2012, CTh3G.4.
  More info

  Abstract: We have developed a technique that allows splicing of liquid core optical fiber (LCOF) to standard fiber with low loss. As an example, we demonstrated ultralow threshold Raman generation in an integrated CS2 filled LCOF. © 2011 Optical Society of America.
• Kieu, K., Norwood, R., & Peyghambarian, N. (2012). Recent progress in mode-locked fiber lasers with carbon nanotube saturable absorber. Fiber Lasers and Applications, FILAS 2012.
  More info

  Abstract: We report our recent results in the development of compact mode-locked fiber lasers with carbon nanotube saturable absorber for various applications. © 2012 OSA.
• Kieu, K., Schneebeli, L., Merzlyak, E., Hales, J. M., DeSimone, A., Perry, J. W., Norwood, R. A., & Peyghambarian, N. (2012). All-optical switching based on inverse Raman scattering in liquid-core optical fibers. Optics Letters, 37(5), 942-944.
  More info

  PMID: 22378446;Abstract: We report on a new platform for all-optical switching based on inverse Raman scattering in liquids. Narrowband switching, which could be suitable for wavelength-division-multiplexed applications, is demonstrated using integrated liquid-core optical fiber infiltrated with both neat liquids (CCl4 and CS2) as well as an organic chromophore (β-carotene) dissolved in CCl4. Compared to standard glass optical fibers, these liquids have much larger Raman loss coefficients, which help reduce the pump power by at least an order of magnitude. Further improvements can be expected with the development of highly soluble organic compounds possessing large Raman cross sections. © 2012 Optical Society of America.
• Kieu, K., Schneebeli, L., Norwood, R. A., & Peyghambarian, N. (2012). Integrated liquid-core optical fibers for ultraefficient nonlinear liquid photonics. Optics Express, 20(7), 8148-8154.
  More info

  PMID: 22453484;Abstract: We have developed a novel integrated platform for liquid photonics based on liquid core optical fiber (LCOF). The platform is created by fusion splicing liquid core optical fiber to standard single-modeoptical fiber making it fully integrated and practical - a major challenge that has greatly hindered progress in liquid-photonic applications. As an example, we report here the realization of ultralow threshold Ramangeneration using an integrated CS2 filled LCOF pumped with subnanosecond pulses at 532nm and 1064nm. The measured energy threshold for the Stokes generation is 1nJ, about three orders of magnitude lower than previously reported values in the literature for hydrogen gas, a popular Raman medium. The integrated LCOF platform opens up new possibilities for ultralow power nonlinear optics such as efficient white light generation for displays, mid-IR generation, slow light generation, parametric amplification, all-optical switching and wavelength conversion using liquids that have orders of magnitude larger optical nonlinearities compared with silica glass. © 2012 Optical Society of America.
• Kim, C., Jung, K., Kieu, K. Q., & Kim, J. (2012). Femtosecond timing jitter from soliton fiber lasers modelocked by carbon nanotube saturable absorbers. Frontiers in Optics, FIO 2012.
  More info

  Abstract: We demonstrate sub-10-fs level timing jitter [integrated from 10 kHz to 40 MHz offset frequency] from 80-MHz soliton Er-fiber lasers mode-locked by carbon nanotube (CNT)-based saturable absorbers. © OSA 2012.
• Kim, C., Jung, K., Kieu, K., & Kim, J. (2012). Low timing jitter and intensity noise from a soliton Er-fiber laser mode-locked by a fiber taper carbon nanotube saturable absorber. Optics Express, 20(28), 29524-29530.
  More info

  PMID: 23388779;Abstract: We characterize the timing jitter and intensity noise of an 80-MHz soliton Er-fiber laser mode-locked by a fiber taper carbon nanotube saturable absorber (ft-CNT-SA) up to the Nyquist frequency. The measured rms timing jitter is 3.0 fs (11.0 fs) integrated from 10 kHz (1 kHz) to 40 MHz offset frequency. The measured rms relative intensity noise (RIN) is 0.069% (0.021%) integrated from 10 Hz to 40 MHz (1 MHz) offset frequency. We identify that the resulting timing jitter is dominated by the Gordon-Haus jitter originated from the negative dispersion necessary for soliton mode-locking with a slow saturable absorber. © 2012 Optical Society of America.
• Makarov, N. S., Lau, P. C., Kieu, K., Norwood, R. A., Peyghambarian, N., & Perry, J. W. (2012). Correlating one-photon, two-photon and excited state spectroscopy of CdSe quantum dots. 2012 Conference on Lasers and Electro-Optics, CLEO 2012.
  More info

  Abstract: We present two-photon absorption and excited-state absorption spectra of quantum dots of various sizes. From the linear and transient spectra we determine transition dipole moments between the states and compare them with the two-photon cross sections. © 2012 OSA.
• Makarov, N. S., Lau, P. C., Kieu, K., Norwood, R. A., Peyghambarian, N., & Perry, J. W. (2012). Correlating one-photon, two-photon and excited state spectroscopy of CdSe quantum dots. CLEO: Applications and Technology, CLEO_AT 2012, JW4A.46.
  More info

  Abstract: We present two-photon absorption and excited-state absorption spectra of quantum dots of various sizes. From the linear and transient spectra we determine transition dipole moments between the states and compare them with the two-photon cross sections. © OSA 2012.
• Makarov, N. S., Lau, P. C., Kieu, K., Norwood, R. A., Peyghambarian, N., & Perry, J. W. (2012). Correlating one-photon, two-photon and excited state spectroscopy of CdSe quantum dots. CLEO: Science and Innovations, CLEO_SI 2012, JW4A.46.
  More info

  Abstract: We present two-photon absorption and excited-state absorption spectra of quantum dots of various sizes. From the linear and transient spectra we determine transition dipole moments between the states and compare them with the two-photon cross sections. © OSA 2012.
• Makarov, N. S., Lau, P. C., Kieu, K., Norwood, R. A., Peyghambarian, N., & Perry, J. W. (2012). Correlating one-photon, two-photon and excited state spectroscopy of CdSe quantum dots. Optics InfoBase Conference Papers.
  More info

  Abstract: We present two-photon absorption and excited-state absorption spectra of quantum dots of various sizes. From the linear and transient spectra we determine transition dipole moments between the states and compare them with the two-photon cross sections. © OSA 2012.
• Oku, M., Kieu, K., & Peyghambarian, N. (2012). High power all-fiber picosecond laser system for UV light generation. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 8237.
  More info

  Abstract: Ultrafast UV and deep UV (DUV) sources are useful for many industrial applications. We present our research on developing a compact and high power picosecond Yb-fiber source for UV light generation (down to ∼ 257 nm wavelength) via single pass second and third harmonics frequency conversion processes. Currently, the laser system delivers 260 mW average power at 343 nm (using THG) and 310 mW at 257 nm (using SHG from 515 nm). © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
• Saynatjoki, A., Karvonen, L., Riikonen, J., Kim, W., Mehravar, S., Norwood, R. A., Peyghambarian, N., Lipsanen, H., & Kieu, K. (2012). Rapid Large-Area Multiphoton Microscopy for Characterization of Graphene. ACS NANO, 7(10), 8441-8446.
  More info

  Single- and few-layer graphene was studied with simultaneous third-harmonic and multiphoton-absorption-excited fluorescence microscopy using a compact 1.55 mu m mode-locked fiber laser source. Strong third-harmonic generation (THG) and multiphoton-absorption-excited fluorescence (MAEF) signals were observed with high contrast over the signal from the substrate. High contrast was also achieved between single- and bilayer graphene. The measurement is straightforward and very fast compared to typical Raman mapping, which is the conventional method for characterization of graphene. Multiphoton microscopy is also proved to be an extremely efficient method for detecting certain structural features in few-layer graphene. The accuracy and speed of multiphoton microscopy make it a very promising characterization technique for fundamental research as well as large-scale fabrication of graphene. To our knowledge, this is the first time simultaneous THG and MAEF microscopy has been utilized in the characterization of graphene. This is also the first THG microscopy study on graphene using the excitation wavelength of 1.55 mu m, which is significant in telecommunications and signal processing.
• Tada, K., Cohoon, G., Kieu, K., Mansuripur, M., & Norwood, R. A. (2012). Fabrication of high-Q microresonators using femtosecond laser micromachining. 2012 Conference on Lasers and Electro-Optics, CLEO 2012.
  More info

  Abstract: We report a novel technique to fabricate microdisk resonators using femtosecond laser micromachining. The resonators had suppressed higher order modes with a measured Q-factor as high as 7.8 x 106. © 2012 OSA.
• Tada, K., Cohoon, G., Kieu, K., Mansuripur, M., & Norwood, R. A. (2012). Fabrication of high-Q microresonators using femtosecond laser micromachining. CLEO: Science and Innovations, CLEO_SI 2012, CM1M.6.
  More info

  Abstract: We report a novel technique to fabricate microdisk resonators using femtosecond laser micromachining. The resonators had suppressed higher order modes with a measured Q-factor as high as 7.8 × 106. © OSA 2012.
• Veiko, V. P., & Kieu, K. K. (2012). Laser amorphisation of glass ceramics: basic properties and new possibilities for manufacturing microoptic elements. QUANTUM ELECTRONICS, 37(1), 92-98.
• Ageev, E., Kieu, K., & Veiko, V. P. (2011). Modification of photosensitive glass-ceramic Foturan by ultra short laser pulses. Proceedings of SPIE - The International Society for Optical Engineering, 7996.
  More info

  Abstract: In this paper laser-induced modification of photosensitive glass-ceramic materials under YAG:Nd second harmonic picosecond pulses is observed. The method for such modification based on laser processing and subsequent heat treatment is developed. The comparison for infrared femtosecond modification is introduced. © 2011 SPIE.
• Fang, Q., Kieu, K., & Peyghambarian, N. (2011). An all-fiber 2μm wavelength tunable mode-locked laser. 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011.
  More info

  Abstract: We propose an all-fiber thulium-doped wavelength tunable mode-locked laser operating near 2 μm. Reliable self-starting mode locking over 50nm tuning range is observed using fiber taper based carbon nanotube (FTCNT) saturable absorber (SA). Spectral tuning is achieved by stretching another fiber taper. © 2011 OSA.
• Fang, Q., Kieu, K., Peyghambarian, N., Fang, Q., Kieu, K., Peyghambarian, N., Fang, Q., Kieu, K., & Peyghambarian, N. (2011). An all-fiber 2μm wavelength tunable mode-locked laser. Optics InfoBase Conference Papers.
  More info

  Abstract: We propose an all-fiber thulium-doped wavelength tunable mode-locked laser operating near 2 μm. Reliable self-starting mode locking over 50nm tuning range is observed using fiber taper based carbon nanotube (FTCNT) saturable absorber (SA). Spectral tuning is achieved by stretching another fiber taper. © 2011 Optical Society of America.
• Kieu, K. Q., Klein, J., Evans, A., Barton, J. K., & Peyghambariana, N. (2011). Ultrahigh resolution all-reflective optical coherence tomography system with a compact fiber-based supercontinuum source. Journal of Biomedical Optics, 16(10).
  More info

  PMID: 22029351;Abstract: We report the construction and characterization of an all-reflective optical coherence tomography (OCT) system using a newly developed compact fiber-based broadband supercontinuum source. The use of only reflective optical components has enabled us to avoid chromatic dispersion effects and to obtain ultrahigh resolution OCT images of biological samples. We achieved an axial resolution of 2 μm in air with 87 dB dynamic range at a center wavelength around 1300 nm. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).
• Kieu, K., & Peyghambarian, N. (2011). Synchronized picosecond pulses at two different wavelengths from a compact fiber laser source for Raman microscopy. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 7903.
  More info

  Abstract: We report on the development of a fiber laser system that supplies synchronized picosecond pulses at two different wavelengths suitable for Raman microscopy. © 2011 SPIE.
• Kieu, K., Jones, R. J., & Peyghambarian, N. (2011). High power femtosecond source near 1 micron based on an all-fiber Er-doped mode-locked laser. 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011.
  More info

  Abstract: We report the design and performance of a high power femtosecond laser source near 1 micron wavelength which is generated from an octave-spanning supercontinuum (SC) pumped by an Er-doped mode-locked laser. © 2011 OSA.
• Kieu, K., Jones, R. J., Peyghambarian, N., Kieu, K., Jones, R. J., Peyghambarian, N., Kieu, K., Jones, R. J., & Peyghambarian, N. (2011). High power femtosecond source near 1 micron based on an all-fiber Er-doped mode-locked laser. Optics InfoBase Conference Papers.
  More info

  Abstract: We report the design and performance of a high power femtosecond laser source near 1 micron wavelength which is generated from an octave-spanning supercontinuum (SC) pumped by an Er-doped mode-locked laser. © 2010 Optical Society of America.
• Kieu, K., Klein, J., Evans, A., Barton, J., & Peyghambarian, N. (2011). Ultrahigh resolution all-reflective OCT system with a compact fiber-based supercontinuum source. 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011.
  More info

  Abstract: We report the construction and characterization of an all-reflective OCT (R-OCT) system using a newly developed compact fiber-based broadband supercontinuum source. We achieved an axial resolution of 1.5 m in tissue (2 m in air) with 87 dB dynamic range at a center wavelength around 1300 nm. © 2011 OSA.
• Kieu, K., Klein, J., Evans, A., Barton, J., & Peyghambarian, N. (2011). Ultrahigh resolution all-reflective OCT system with a compact fiber-based supercontinuum source. Optics InfoBase Conference Papers.
  More info

  Abstract: We report the construction and characterization of an all-reflective OCT (R-OCT) system using a newly developed compact fiber-based broadband supercontinuum source. We achieved an axial resolution of 1.5 μm in tissue (2 μm in air) with 87 dB dynamic range at a center wavelength around 1300 nm. © 2010 Optical Society of America.
• Kieu, K., Schneebeli, L., Hales, J. M., Perry, J. W., Norwood, R. A., & Peyghambarian, N. (2011). All-optical switching via inverse Raman scattering in an optical fiber. 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011.
  More info

  Abstract: We report the observation of inverse Raman scattering (IRS) in optical fiber. The achieved level of attenuation via IRS in an optical fiber is > 20dB at a time scale < 5ps. We found good agreement between experimental data and theoretical calculations. © 2011 OSA.
• Kieu, K., Schneebeli, L., Hales, J. M., Perry, J. W., Norwood, R. A., & Peyghambarian, N. (2011). All-optical switching via inverse Raman scattering in an optical fiber. Optics InfoBase Conference Papers.
  More info

  Abstract: We report the observation of inverse Raman scattering (IRS) in optical fiber. The achieved level of attenuation via IRS in an optical fiber is > 20dB at a time scale < 5ps. We found good agreement between experimental data and theoretical calculations. © 2010 Optical Society of America.
• Kieu, K., Schneebeli, L., Hales, J. M., Perry, J. W., Norwood, R. A., & Peyghambarian, N. (2011). Demonstration of Zeno switching through inverse Raman scattering in an optical fiber. Optics Express, 19(13), 12532-12539.
  More info

  PMID: 21716494;Abstract: We report the observation of Zeno switching through an inverse Raman scattering (IRS) process in an optical fiber. In IRS, light at the anti-Stokes frequency is strongly attenuated in the presence of a pump field, allowing it to be used for all-optical switching and modulation. Our observed level of induced absorption via IRS in the optical fiber is > 20dB in a time scale of less than 5 ps. The full Raman response spectrum was extracted experimentally and excellent agreement was found between the experimental data and theoretical modeling of IRS. © 2011 Optical Society of America.
• Kieu, K., Schneebeli, L., Merzlyak, E., Hales, J. M., DeSimone, A., Perry, J. W., Norwood, R. A., & Peyghambarian, N. (2011). All-optical switching based on inverse Raman scattering in liquid-core optical fibers. OPTICS LETTERS, 37(5), 942-944.
  More info

  We report on a new platform for all-optical switching based on inverse Raman scattering in liquids. Narrowband switching, which could be suitable for wavelength-division-multiplexed applications, is demonstrated using integrated liquid-core optical fiber infiltrated with both neat liquids (CCl4 and CS2) as well as an organic chromophore (beta-carotene) dissolved in CCl4. Compared to standard glass optical fibers, these liquids have much larger Raman loss coefficients, which help reduce the pump power by at least an order of magnitude. Further improvements can be expected with the development of highly soluble organic compounds possessing large Raman cross sections. (C) 2012 Optical Society of America
• Kieu, K., Schneebeli, L., Norwood, R. A., & Peyghambarian, N. (2011). Integrated liquid-core optical fibers for ultra-efficient nonlinear liquid photonics. OPTICS EXPRESS, 20(7), 8148-8154.
  More info

  We have developed a novel integrated platform for liquid photonics based on liquid core optical fiber (LCOF). The platform is created by fusion splicing liquid core optical fiber to standard single-mode optical fiber making it fully integrated and practical - a major challenge that has greatly hindered progress in liquid-photonic applications. As an example, we report here the realization of ultralow threshold Raman generation using an integrated CS2 filled LCOF pumped with sub-nanosecond pulses at 532nm and 1064nm. The measured energy threshold for the Stokes generation is 1nJ, about three orders of magnitude lower than previously reported values in the literature for hydrogen gas, a popular Raman medium. The integrated LCOF platform opens up new possibilities for ultralow power nonlinear optics such as efficient white light generation for displays, mid-IR generation, slow light generation, parametric amplification, all-optical switching and wavelength conversion using liquids that have orders of magnitude larger optical nonlinearities compared with silica glass. (C) 2012 Optical Society of America
• Liu, G., Kieu, K., Wise, F. W., & Chen, Z. (2011). Multiphoton microscopy system with a compact fiber-based femtosecond-pulse laser and handheld probe. Journal of Biophotonics, 4(1-2), 34-39.
  More info

  PMID: 20635426;PMCID: PMC3337208;Abstract: We report on the development of a compact multiphoton microscopy (MPM) system that integrates a compact and robust fiber laser with a miniature probe. The all normal dispersion fiber femtosecond laser has a central wavelength of 1.06 μm, pulse width of 125 fs and average power of more than 1 W. A double cladding photonic crystal fiber was used to deliver the excitation beam and to collect the two-photon signal. The hand-held probe included galvanometer-based mirror scanners, relay lenses and a focusing lens. The packaged probe had a diameter of 16 mm. Second harmonic generation (SHG) images and two-photon excited fluorescence (TPEF) images of biological tissues were demonstrated using the system. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
• Liu, H., Kieu, K., Lefrancois, S., Renninger, W. H., Chong, A., & Wise, F. W. (2011). Tm fiber laser mode-locked at large normal dispersion. 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011.
  More info

  Abstract: We demonstrate a mode-locked Tm fiber laser at large normal dispersion, generating 0.4 nJ pulses dechirping to 470 fs. The dispersion is controlled in an all fiber format. © 2011 OSA.
• Liu, H., Kieu, K., Lefrancois, S., Renninger, W. H., Chong, A., & Wise, F. W. (2011). Tm fiber laser mode-locked at large normal dispersion. Optics InfoBase Conference Papers.
  More info

  Abstract: We demonstrate a mode-locked Tm fiber laser at large normal dispersion, generating 0.4 nJ pulses dechirping to 470 fs. The dispersion is controlled in an all fiber format. © OSA/CLEO 2011.
• Richards, B. C., Hendrickson, J., Olitzky, J. D., Gibson, R., Gehl, M., Kieu, K., Khankhoje, U. K., Homyk, A., Scherer, A., Kim, J. -., Lee, Y. -., Khitrova, G., & Gibbs, H. M. (2011). Characterization of 1D photonic crystal nanobeam cavities using curved microfiber. OPTICS EXPRESS, 18(20), 20558-20564.
  More info

  We investigate high-Q, small mode volume photonic crystal nanobeam cavities using a curved, tapered optical microfiber loop. The strength of the coupling between the cavity and the microfiber loop is shown to depend on the contact position on the nanobeam, angle between the nanobeam and the microfiber, and polarization of the light in the fiber. The results are compared to a resonant scattering measurement. (C) 2010 Optical Society of America
• Schneebeli, L., Kieu, K., Merzlyak, E., Hales, J. M., DeSimone, A., Perry, J. W., Norwood, R. A., & Peyghambarian, N. (2011). Measurement of the Raman gain coefficient via inverse Raman scattering. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, 30(11), 2930-2939.
  More info

  We report a new characterization technique of Raman gain materials through inverse Raman scattering (IRS). The technique is applied to silica glass optical fiber and several liquids in liquid-core optical fiber (LCOF). We obtain good quantitative agreement with a conventional technique that estimates the gain coefficient from steady-state Raman scattering measurements. Our results demonstrate that IRS is a viable tool to characterize new materials for ultralow-power nonlinear optics and all-optical switching. (C) 2013 Optical Society of America
• Wu, T., Kieu, K., Peyghambarian, N., & Jones, R. J. (2011). Low noise erbium fiber fs frequency comb based on a tapered-fiber carbon nanotube design. OPTICS EXPRESS, 19(6), 5313-5318.
  More info

  We report on a low noise all-fiber erbium fs frequency comb based on a simple and robust tapered-fiber carbon nanotube (tf-CNT) design. We mitigate dominant noise sources to show that the free-running linewidth of the carrier-envelope offset frequency (f(ceo)) can be comparable to the best reported performance to date for fiber-based frequency combs. A free-running f(ceo) linewidth of similar to 20 kHz is demonstrated, corresponding to an improvement of similar to 30 times over previous work based on a CNT mode-locked fiber laser [Opt. Express 18, 1667 (2010)]. We also demonstrate the use of an acousto-optic modulator external to the laser cavity to stabilize f(ceo), enabling a 300 kHz feedback control bandwidth. The offset frequency is phase-locked with an in-loop integrated phase noise of similar to 0.8 rad from 10Hz to 400kHz. We show a resolution-limited linewidth of similar to 1 Hz, demonstrating over 90% of the carrier power within the coherent f(ceo) signal. The results demonstrate that the relatively simple tf-CNT fiber laser design can provide a compact, robust and high-performance fs frequency comb. (C) 2011 Optical Society of America
• Wu, T., Kieu, K., Peyghambarian, N., & Jones, R. J. (2011). Low noise erbium fiber fs frequency comb based on a tapered-fiber carbon nanotube design. Optics Express, 19(6), 5313-5318.
  More info

  PMID: 21445169;Abstract: We report on a low noise all-fiber erbium fs frequency comb based on a simple and robust tapered-fiber carbon nanotube (tf-CNT) design. We mitigate dominant noise sources to show that the free-running linewidth of the carrier-envelope offset frequency (fceo) can be comparable to the best reported performance to date for fiber-based frequency combs. A free-running fceo linewidth of ∼20 kHz is demonstrated, corresponding to an improvement of ∼30 times over previous work based on a CNT mode-locked fiber laser [Opt. Express 18, 1667(2010)]. We also demonstrate the use of an acousto-optic modulator external to the laser cavity to stabilize f ceo, enabling a 300 kHz feedback control bandwidth. The offset frequency is phase-locked with an in-loop integrated phase noise of ∼0.8 rad from 10Hz to 400kHz. We show a resolution-limited linewidth of ∼1 Hz, demonstrating over 90% of the carrier power within the coherent fceo signal. The results demonstrate that the relatively simple tf-CNT fiber laser design can provide a compact, robust and high-performance fs frequency comb. © 2011 Optical Society of America.
• Zhu, X., Schülzgen, A., Wei, H., Kieu, K., & Peyghambarian, N. (2011). White light Bessel-like beams generated by miniature all-fiber device. Optics Express, 19(12), 11365-11374.
  More info

  PMID: 21716366;Abstract: Micron-sized white light propagation invariant beams generated by a simple and compact fiber device are presented. The all-fiber device is fabricated by splicing a short piece of large-core multimode fiber onto a small-core single mode white light delivery fiber. Because this fiber device offers an inherent spatial coherence, nondiffracting white light beams can be created with a temporally incoherent broadband light source (a halogen bulb) and, most importantly, the surrounding fringes don?t fade as the bandwidth of the light source increases because the underlying physics of this fiber device is different from that of the axicon. White light Bessel-like beams have been generated from multimode fibers with core diameters of 50 μm, 105 μm, and 200 μm. The distance of nondiffracting propagation of the white light Bessel beam increases with increasing core size of the multimode fiber. Propagation characteristics of red, green, and blue individual beams are also presented. © 2011 Optical Society of America.
• Alasaarela, T., Karvonen, L., Jussila, H., Saynatjoki, A., Mehravar, S., Norwood, R. A., Peyghambarian, N., Kieu, K., Tittonen, I., & Lipsanen, H. (2010). High-quality crystallinity controlled ALD TiO2 for waveguiding applications. OPTICS LETTERS, 38(20), 3980-3983.
  More info

  We demonstrate a novel atomic layer deposition (ALD) process to make high-quality nanocrystalline titanium dioxide (TiO2) with intermediate Al2O3 layers to limit the crystal size. The process is based on titanium chloride (TiCl4) + water and trimethyl aluminum (TMA) + ozone processes at 250 degrees C deposition temperature. The waveguide losses measured using a prism coupling method for 633 and 1551 nm wavelengths are as low as 0.2 +/- 0.1 dB/mm with the smallest crystal size, with losses increasing with crystal size. In comparison, plain TiO2 deposited at 250 degrees C without the intermediate Al2O3 layers shows high scattering losses and is not viable as waveguide material. The third-order optical nonlinearity decreases with smaller crystal size as verified by third-harmonic generation microscopy but still remains high for all samples. Crystallinity controlled ALD-grown TiO2 is an excellent candidate for various optical applications, where good thermal stability and high third-order optical nonlinearity are needed. (C) 2013 Optical Society of America
• Bale, B. G., Kieu, K., Kutz, J. N., & Wise, F. (2010). Transition dynamics for multi-pulsing in mode-locked lasers. Optics InfoBase Conference Papers.
  More info

  Abstract: We consider experimentally and theoretically a refined parameter space in a mode-locked fiber laser near the transition to multi-pulsing. Increasing cavity energy drives the dynamics through a periodic instability to chaotic dynamics. © 2010 Optical Society of America.
• Bale, B. G., Kieu, K., Wise, F., & Kutz, J. N. (2010). Characterizing the transition dynamics for multi-pulsing in mode-locked lasers. Proceedings of SPIE - The International Society for Optical Engineering, 7580.
  More info

  Abstract: We consider experimentally and theoretically a refined parameter space near the transition to multi-pulse modelocking. Near the transition, the onset of instability is initiated by a Hopf (periodic) bifurcation. As cavity energy is increased, the band of unstable, oscillatory modes generates a chaotic behavior between single- and multi-pulse operation. Both theory and experiment are in good qualitative agreement and they suggest that the phenomenon is of a universal nature in mode-locked lasers at the onset of multi-pulsing from N to N + 1 pulses per round trip. This is the first theoretical and experimental characterization of the transition behavior, made possible by a highly refined tuning of the gain pump level. © 2010 Copyright SPIE - The International Society for Optical Engineering.
• Fang, Q., Kieu, K., & Peyghambarian, N. (2010). An All-fiber 2-μm wavelength-tunable mode-locked laser. IEEE Photonics Technology Letters, 22(22), 1656-1658.
  More info

  Abstract: We report an all-fiber thulium-doped wavelength-tunable mode-locked laser operating near 2 μm. Reliable self-starting mode locking over a large tuning range (>50 nm) using a fiber-taper-based carbon nanotube saturable absorber is observed. Spectral tuning is achieved by stretching another fiber taper. To the best of our knowledge, this is the first demonstration of an all-fiber wavelength tunable mode-locked laser near 2 μm. © 2010 IEEE.
• Kieu, K., & Mansuripur, M. (2010). Tuning of fiber lasers by use of a single-mode biconic fiber taper. OPTICS LETTERS, 31(16), 2435-2437.
  More info

  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. (c) 2006 Optical Society of America.
• Kieu, K., Jones, J. R., & Peyghambarian, N. (2010). Generation of sub-20fs pulses from an all-fiber carbon nanotube mode-locked laser system. Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference: 2010 Laser Science to Photonic Applications, CLEO/QELS 2010.
  More info

  Abstract: We report a simple all-fiber femtosecond laser system based on carbon nanotube saturable absorber that was capable of generating 17-fs pulses with optical spectrum extending from 1000 nm to 1750 nm. © 2009 Optical Society of America.
• Kieu, K., Jones, J. R., & Peyghambarian, N. (2010). Generation of sub-20fs pulses from an all-fiber carbon nanotube mode-locked laser system. Optics InfoBase Conference Papers.
  More info

  Abstract: We report a simple all-fiber femtosecond laser system based on carbon nanotube saturable absorber that was capable of generating 17-fs pulses with optical spectrum extending from 1000 nm to 1750 nm. © 2009 Optical Society of America.
• Kieu, K., Jones, R. J., & Peyghambarian, N. (2010). Generation of few-cycle pulses from an amplified carbon nanotube mode-locked fiber laser system. IEEE Photonics Technology Letters, 22(20), 1521-1523.
  More info

  Abstract: We report a simple femtosecond fiber laser system based on a carbon nanotube saturable absorber that is capable of generating 14-fs pulses (containing less than four optical cycles) with optical spectrum extending from 1000 nm to around 1500 nm. © 2006 IEEE.
• Kieu, K., Jones, R. J., & Peyghambarian, N. (2010). High power femtosecond source near 1 micron based on an all-fiber Er-doped mode-locked laser. OPTICS EXPRESS, 18(20), 21350-21355.
  More info

  We report the design and performance of a high power femtosecond laser source near 1 micron wavelength which is generated from an octave-spanning supercontinuum ( SC) pumped by an Er-doped mode-locked laser. The laser system delivers >5W average power at 35MHz repetition rate and 135 fs pulse duration. (C) 2010 Optical Society of America
• Kieu, K., Jones, R. J., & Peyghambarian, N. (2010). High power femtosecond source near 1 micron based on an all-fiber Er-doped mode-locked laser. Optics Express, 18(20), 21350-21355.
  More info

  PMID: 20941031;Abstract: We report the design and performance of a high power femtosecond laser source near 1 micron wavelength which is generated from an octave-spanning supercontinuum (SC) pumped by an Er-doped mode-locked laser. The laser system delivers>5W average power at 35MHz repetition rate and 135 fs pulse duration. © 2010 Optical Society of America.
• Kieu, K., Saar, B. G., Holtom, G. R., Xie, S. X., & Wise, F. W. (2010). Picosecond fiber source for coherent Raman microscopy. Optics InfoBase Conference Papers.
  More info

  Abstract: We report a high power picosecond fiber laser system for coherent Raman microscopy (CRM). The laser system was used to pump an optical parametric oscillator to produce the pump and the Stokes beams for CRM. © 2009 Optical Society of America.
• Kieu, K., Saar, B. G., Holtom, G. R., Xie, X. S., & Wise, F. W. (2010). High-power picosecond fiber source for coherent Raman microscopy. OPTICS LETTERS, 34(13), 2051-2053.
  More info

  We report a high-power picosecond fiber pump laser system for coherent Raman microscopy (CRM). The fiber laser system generates 3.5 ps pulses with 6 W average power at 1030 nm. Frequency doubling yields more than 2 W of green light, which can be used to pump an optical parametric oscillator to produce the pump and the Stokes beams for CRM. Detailed performance data on the laser and the various wavelength conversion steps are discussed, together with representative CRM images of fresh animal tissue obtained with the new source. (C) 2009 Optical Society of America
• Kieu, K., Schneebeli, L., Norwood, R. A., & Peyghambarian, N. (2010). Zeno switching through inverse Raman scattering in optical fiber. Optics and Photonics News, 21(12), 35-.
  More info

  Abstract: A number of researchers have conducted investigations to demonstrate Zeno switching through inverse Raman scattering (IRS) in optical fiber. Zeno switching refers to switching of a signal optical beam in the presence of a control-pump beam in which neither beam is separately absorbed. Light at the anti-Stokes frequency is strongly attenuated in the presence of a pump field. The switching contrast that is determined by the observed level of induced absorption via IRS in the optical fiber is more than 20 dB in a time scale of less than 5 ps. Researchers have extracted the full Raman response function experimentally and found excellent agreement between theory and experiment. IRS has also been found to be a good candidate to build a Zeno-type all-optical switch due to specific scattering characteristics.
• Kieu, K., Wu, T., Peyghambarian, N., & Jones, R. J. (2010). All-fiber carbon nanotube based mode-locked laser system for generation of stable fs frequency combs. Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference: 2010 Laser Science to Photonic Applications, CLEO/QELS 2010.
  More info

  Abstract: We report on a simplified all-fiber octave spanning femtosecond laser system based on a tapered fiber carbon nanotube saturable absorber capable of generating a stabilized frequency comb structure. © 2009 Optical Society of America.
• Kieu, K., Wu, T., Peyghambarian, N., & Jones, R. J. (2010). All-fiber carbon nanotube based mode-locked laser system for generation of stable fs frequency combs. Optics InfoBase Conference Papers.
  More info

  Abstract: We report on a simplified all-fiber octave spanning femtosecond laser system based on a tapered fiber carbon nanotube saturable absorber capable of generating a stabilized frequency comb structure. © 2010 Optical Society of America.
• Lefrançois, S., Kieu, K., Deng, Y., Kafka, J. D., & Wise, F. W. (2010). Scaling of dissipative soliton fiber lasers to megawatt peak powers by use of large-area photonic crystal fiber. Optics Letters, 35(10), 1569-1571.
  More info

  PMID: 20479811;PMCID: PMC3135629;Abstract: We report an all-normal dispersion femtosecond laser based on large-mode-area Yb-doped photonic crystal fiber. Self-starting mode-locked pulses are obtained with an average power of 12 W at 84 MHz repetition rate, corresponding to 140 nJ of chirped pulse energy. These are dechirped to a near transform-limited duration of 115 fs. Experimental results are consistent with numerical simulations of dissipative soliton intracavity pulse evolution, and demonstrate scaling of 100 fs pulses to megawatt peak powers. © 2010 Optical Society of America.
• Lefrançois, S., Kieu, K., Wise, F. W., Deng, Y., & Kafka, J. D. (2010). Photonic crystal fiber based dissipative soliton laser for multi-Watt femtosecond mode-locking. Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference: 2010 Laser Science to Photonic Applications, CLEO/QELS 2010.
  More info

  Abstract: We report on photonic crystal fiber based scaling of the mode-area of a dissipative soliton laser. The laser delivers 142 nJ chirped pulses with 12 W average power, dechirping to 105 fs after extra-cavity compression. © 2010 Optical Society of America.
• Lefrançois, S., Kieu, K., Wise, F. W., Deng, Y., & Kafka, J. D. (2010). Photonic crystal fiber based dissipative soliton laser for multi-Watt femtosecond mode-locking. Optics InfoBase Conference Papers.
  More info

  Abstract: We report on photonic crystal fiber based scaling of the mode-area of a dissipative soliton laser. The laser delivers 142 nJ chirped pulses with 12 W average power, dechirping to 105 fs after extra-cavity compression.© 2010 Optical Society of America.
• Lefrançois, S., Kieu, K., Wise, F. W., Deng, Y., & Kafka, J. D. (2010). Scaling of dissipative soliton lasers to megawatt peak powers. Optics InfoBase Conference Papers.
  More info

  Abstract: Dissipative solitons can be stable despite huge nonlinear phase shifts. We exploit this property and scaling at constant nonlinear phase to demonstrate a femtosecond fiber laser with peak power 4 times greater than prior lasers. © 2010 Optical Society of America.
• Liu, G., Kieu, K., Wise, F. W., & Chen, Z. (2010). Fiber-based multiphoton system. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 7569.
  More info

  Abstract: A fiber based multiphoton microscopy (MPM) system is designed and demonstrated. An all normal dispersion fiber laser with central wavelength around 1um was used as laser source. A double clad photonic crystal fiber (DCPCF), and galvanometer mirror scanner based handheld probe is designed. Second harmonic generation (SHG) images and two photon excited fluorescence (TPEF) images of biological tissue were demonstrated by the system. © 2010 Copyright SPIE - The International Society for Optical Engineering.
• Liu, G., Kieu, K., Wise, F. W., & Chen, Z. (2010). Multiphoton microscopy system with a compact fiber-based femtosecond-pulse laser and handheld probe. JOURNAL OF BIOPHOTONICS, 4(1-2), 34-39.
  More info

  We report on the development of a compact multiphoton microscopy (MPM) system that integrates a compact and robust fiber laser with a miniature probe. The all normal dispersion fiber femtosecond laser has a central wavelength of 1.06 mu m, pulse width of 125 fs and average power of more than 1 W. A double cladding photonic crystal fiber was used to deliver the excitation beam and to collect the two-photon signal. The hand-held probe included galvanometer-based mirror scanners, relay lenses and a focusing lens. The packaged probe had a diameter of 16 mm. Second harmonic generation (SHG) images and two-photon excited fluorescence (TPEF) images of biological tissues were demonstrated using the system.
• Liu, G., Kieu, K., Wise, F. W., Wong, B., & Chen, Z. (2010). Fiber-based microendoscopic multiphoton imaging. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 7548.
  More info

  Abstract: We developed a multiphoton microscope which integrates an all normal dispersion fiber laser, a double cladding photonic crystal fiber and a MEMS mirror scanner based hand-held probe. The fiber laser has a central wavelength of 1.06μm,a repetition rate of 76MHz and maximum average output power of more than 1W. The MEMS mirror based probe is compact and Second harmonic generation and two photon excited fluorescence images of biological sample were demonstrated. © 2010 Copyright SPIE - The International Society for Optical Engineering.
• Shahin, S., Kieu, K., Hales, J. M., Kim, H., Getmanenko, Y. A., Zhang, Y., Perry, J. W., Marder, S. R., Norwood, R. A., & Peyghambarian, N. (2010). Third-order nonlinear optical characterization of organic chromophores using liquid-core optical fibers. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, 31(10), 2455-2459.
  More info

  We present our technique to characterize the third-order nonlinear optical properties of organic dyes in our previously introduced integrated liquid-core optical fiber (i-LCOF) platform. i-LCOF is filled with the solution of the organic dyes, and the change in the laser pulse spectral width due to self-phase modulation is investigated. The measurements are done at 1550 nm using a mode-locked femtosecond fiber laser. The solution/laser interaction length is long (similar to 50 cm), which removes the need for high-power pump pulses. This method is fast, simple, and can be extended to the characterization of other nanoscale particles such as quantum dots and plasmonic metal nanoparticles in solutions. (C) 2014 Optical Society of America
• Wise, F. W., Renninger, W., Lefrancois, S., Kieu, K., Farrar, M., Schaffer, C., Saar, B., Holtom, G., & Xie, S. (2010). Short-pulse fiber lasers for Raman microscopies. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 7569.
  More info

  Abstract: Recent developments in femtosecond and picosecond fiber sources for application to coherent Raman microscopies are reviewed. © 2010 Copyright SPIE - The International Society for Optical Engineering.
• Bale, B. G., Kieu, K., Kutz, J. N., & Wise, F. (2009). Transition dynamics for multi-pulsing in mode-locked lasers. OPTICS EXPRESS, 17(25), 23137-23146.
  More info

  We consider experimentally and theoretically a refined parameter space in a laser system near the transition to multi-pulse mode-locking. Near the transition, the onset of instability is initiated by a Hopf (periodic) bifurcation. As the cavity energy is increased, the band of unstable, oscillatory modes generates a chaotic behavior between single-and multi-pulse operation. Both theory and experiment are in good qualitative agreement and they suggest that the phenomenon is of a universal nature in mode-locked lasers at the onset of multi-pulsing from N to N + 1 pulses per round trip. This is the first theoretical and experimental characterization of the transition behavior, made possible by a highly refined tuning of the gain pump level. (C) 2009 Optical Society of America
• Bale, B. G., Kieu, K., Kutz, J. N., & Wise, F. (2009). Transition dynamics for multi-pulsing in mode-locked lasers. Optics Express, 17(25), 23137-23146.
  More info

  PMID: 20052241;Abstract: We consider experimentally and theoretically a refined parameter space in a laser system near the transition to multi-pulse modelocking. Near the transition, the onset of instability is initiated by a Hopf (periodic) bifurcation. As the cavity energy is increased, the band of unstable, oscillatory modes generates a chaotic behavior between single- and multi-pulse operation. Both theory and experiment are in good qualitative agreement and they suggest that the phenomenon is of a universal nature in mode-locked lasers at the onset of multi-pulsing from N to N +1 pulses per round trip. This is the first theoretical and experimental characterization of the transition behavior, made possible by a highly refined tuning of the gain pump level. © 2009 Optical Society of America.
• Himmelhuber, R., Mehravar, S. S., Herrera, O. D., Demir, V., Kieu, K., Luo, J., Jen, A. K., Norwood, R. A., & Peyghambarian, N. (2009). Characterization of coplanar poled electro optic polymer films for Si-photonic devices with multiphoton microscopy. APPLIED PHYSICS LETTERS, 104(16).
  More info

  We imaged coplanar poled electro optic (EO) polymer films on transparent substrates with a multiple-photon microscope in reflection and correlated the second-harmonic light intensity with the results of Pockels coefficient (r(33)) measurements. This allowed us to make quantitative measurements of poled polymer films on non-transparent substrates like silicon, which are not accessible with traditional Pockels coefficient measurement techniques. Phase modulators consisting of silicon waveguide devices with EO polymer claddings with a known Pockels coefficient (from V-pi measurements) were used to validate the correlation between the second-harmonic signal and r(33). This also allowed us to locally map the r(33) coefficient in the poled area. (C) 2014 AIP Publishing LLC.
• Kieu, K., & Mansuripur, M. (2009). Femtosecond laser pulse generation with a fiber taper embedded in carbon nanotube/polymer composite. OPTICS LETTERS, 32(15), 2242-2244.
  More info

  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. (c) 2007 Optical Society of America.
• Kieu, K., & Wise, F. W. (2009). All-fiber normal-dispersion femtosecond laser. OPTICS EXPRESS, 16(15), 11453-11458.
  More info

  Spectral filtering of a chirped pulse can be a strong pulse-shaping mechanism in all-normal-dispersion femtosecond fiber lasers. We report an implementation of such a laser that employs only fiber-format components. The Yb-doped fiber laser includes a fiber filter, and a saturable absorber based on carbon nanotubes. The laser generates 1.5-ps, 3-nJ pulses that can be dechirped to 250 fs duration outside the cavity. (C) 2008 Optical Society of America.
• Kieu, K., & Wise, F. W. (2009). Mode-locked Thulium-doped fiber laser with carbon nanotube saturable absorber. 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009.
  More info

  Abstract: We report mode-locking of an all-fiber thulium/holmium (Tm/Ho) co-doped laser with a saturable absorber based on a fiber taper embedded in carbon nanotube/polymer composite (FTCNTPC). 750fs soliton pulses are generated at wavelength around 1890nm. ©2008 Optical Society of America.
• Kieu, K., & Wise, F. W. (2009). Mode-locked Thulium-doped fiber laser with carbon nanotube saturable absorber. Optics InfoBase Conference Papers.
  More info

  Abstract: We report mode-locking of an all-fiber thulium/holmium (Tm/Ho) co-doped laser with a saturable absorber based on a fiber taper embedded in carbon nanotube/polymer composite (FTCNTPC). 750fs soliton pulses are generated at wavelength around 1890nm. © 2009 Optical Society of America.
• Kieu, K., & Wise, F. W. (2009). Self-similar and stretched-pulse operation of erbium-doped fiber lasers with carbon nanotubes saturable absorber. 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009.
  More info

  Abstract: We report self-similar and stretched -pulse operations in an all-fiber erbium-doped laser using carbon nanotube saturable absorber, for the first time. Pulses as short as 115fs are achieved in the stretched-pulse regime. ©2008 Optical Society of America.
• Kieu, K., & Wise, F. W. (2009). Self-similar and stretched-pulse operation of erbium-doped fiber lasers with carbon nanotubes saturable absorber. Optics InfoBase Conference Papers.
  More info

  Abstract: We report self-similar and stretched -pulse operations in an all-fiber erbium-doped laser using carbon nanotube saturable absorber, for the first time. Pulses as short as 115fs are achieved in the stretched-pulse regime. © 2009 Optical Society of America.
• Kieu, K., & Wise, F. W. (2009). Soliton thulium-doped fiber laser with carbon nanotube saturable absorber. IEEE Photonics Technology Letters, 21(3), 128-130.
  More info

  Abstract: We report stabilization of a thulium-holmium codoped fiber soliton laser with a saturable absorber based on carbon nanotubes. The laser generates transform-limited 750-fs pulses with 0.5-nJ energy. © 2009 IEEE.
• Kieu, K., Renninger, W. H., Chong, A., & Wise, F. W. (2009). Sub-100 fs pulses at watt-level powers from a dissipative-soliton fiber laser. OPTICS LETTERS, 34(5), 593-595.
  More info

  We report a mode-locked fiber laser that exploits dissipative-soliton pulse shaping along with cladding pumping for high average power. The laser generates 31 nJ chirped pulses at 70 MHz repetition rate, for an average power of 2.2 W. After dechirping outside the laser, 80 fs pulses, with 200 kW peak power, are obtained. (C) 2009 Optical Society of America
• Kieu, K., Renninger, W. H., Chong, A., & Wise, F. W. (2009). Sub-100 fs pulses at watt-level powers from a dissipative-soliton fiber laser. Optics Letters, 34(5), 593-595.
  More info

  PMID: 19252562;PMCID: PMC3127441;Abstract: We report a mode-locked fiber laser that exploits dissipative-soliton pulse shaping along with cladding pumping for high average power. The laser generates 31 nJ chirped pulses at 70 MHz repetition rate, for an average power of 2.2 W. After dechirping outside the laser, 80 fs pulses, with 200 kW peak power, are obtained. © 2009 Optical Society of America.
• Kieu, K., Renninger, W., Chong, A., & Wise, F. W. (2009). Mode-locked Yb-doped fiber laser with Watt-level average power and sub-100fs pulse duration. 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009.
  More info

  Abstract: We report a pulsed fiber laser that generates 31-nJ chirped pulses at 70-MHz repetition rate and 2.2 W average power. After dechirping outside the cavity, 80-fs pulses, with 200-kW peak power, are obtained. ©2008 Optical Society of America.
• Kieu, K., Renninger, W., Chong, A., & Wise, F. W. (2009). Mode-locked Yb-doped fiber laser with Watt-level average power and sub-100fs pulse duration. Optics InfoBase Conference Papers.
  More info

  Abstract: We report a pulsed fiber laser that generates 31-nJ chirped pulses at 70-MHz repetition rate and 2.2 W average power. After dechirping outside the cavity, 80-fs pulses, with 200-kW peak power, are obtained. © 2009 Optical Society of America.
• Kieu, K., Renninger, W., Chong, A., & Wise, F. W. (2009). Sub-100-fs pulses at watt-level powers from a fiber laser. Optics InfoBase Conference Papers.
  More info

  Abstract: We report a mode-locked fiber laser that generates 31-nJ chirped pulses at 70-MHz repetition rate, for an average power of 2.2 W. After dechirping outside the cavity, 80-fs pulses, with 200-kW peak power, are obtained. © 2008 Optical Society of America.
• Kieu, K., Saar, B. G., Holtom, G. R., Xie, X. S., & Wise, F. W. (2009). High-power picosecond fiber source for coherent Raman microscopy. Optics Letters, 34(13), 2051-2053.
  More info

  PMID: 19571996;PMCID: PMC3142585;Abstract: We report a high-power picosecond fiber pump laser system for coherent Raman microscopy (CRM). The fiber laser system generates 3.5 ps pulses with 6 W average power at 1030 nm. Frequency doubling yields more than 2 W of green light, which can be used to pump an optical parametric oscillator to produce the pump and the Stokes beams for CRM. Detailed performance data on the laser and the various wavelength conversion steps are discussed, together with representative CRM images of fresh animal tissue obtained with the new source. © 2009 Optical Society of America.
• Liu, G., Chen, Z., Kieu, K., & Wise, F. W. (2009). Fiber based multiphoton microscope using a fiber femtosecond laser and MEMS scanning probe. Optics InfoBase Conference Papers.
  More info

  Abstract: We developed a fiber based MPM that integrates an all-normal-dispersion femtosecond fiber laser, double cladding photonic crystal fiber, and a MEMS scanning probe. Second harmonic generation and two photon excited fluorescence images of biological samples were demonstrated. © 2009 Optical Society of America.
• Wise, F. W., Kieu, K., Saar, B., Holtom, G., & Xie, S. (2009). Fiber lasers for CARS microscopy. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 7183.
  More info

  Abstract: We report a fiber-based high-power picosecond laser system for coherent Raman microscopy (CRM). This source generates 3-ps pulses with 6 W average power at 1030 nm. Frequency-doubling yields more than 2 W of green light, which can be used to pump a commercial optical parametric oscillator to produce the pump and Stokes beams for CRM. The design and performance of the laser are described, along with an application to CARS imaging. © 2009 SPIE.
• Kieu, K., & Mansuripur, M. (2008). All-fiber bidirectional passively mode-locked ring laser. OPTICS LETTERS, 33(1), 64-66.
  More info

  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. (c) 2007 Optical Society of America.
• Kieu, K., & Mansuripur, M. (2008). All-fiber idirectional passively mode-locked ring laser. Optics Letters, 33(1), 64-66.
  More info

  PMID: 18157259;Abstract: 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. © 2007 Optical Society of America.
• Kieu, K., & Wise, F. W. (2008). All-fiber normal-dispersion femtosecond laser. Optics Express, 16(15), 11453-11457.
  More info

  PMID: 18648465;PMCID: PMC3142586;Abstract: Spectral filtering of a chirped pulse can be a strong pulse-shaping mechanism in all-normal-dispersion femtosecond fiber lasers. We report an implementation of such a laser that employs only fiber-format components. The Yb-doped fiber laser includes a fiber filter, and a saturable absorber based on carbon nanotubes. The laser generates 1.5-ps, 3-nJ pulses that can be dechirped to 250 fs duration outside the cavity. © 2008 Optical Society of America.
• Kieu, K., & Wise, F. W. (2008). Soliton Thulium-Doped Fiber Laser With Carbon Nanotube Saturable Absorber. IEEE PHOTONICS TECHNOLOGY LETTERS, 21(1-4), 128-130.
  More info

  We report stabilization of a thulium-holmium codoped fiber soliton laser with a saturable absorber based on carbon nanotubes. The laser generates transform-limited 750-fs pulses with 0.5-nJ energy.
• Kim, Y., Lu, P., Milster, T. D., & Kieu, K. (2008). Hyper-numerical aperture (NA=2.8) microscope using lambda=1.56 mu m femtosecond source for multi-photon imaging. BIOMEDICAL OPTICS EXPRESS, 4(10), 1786-1794.
  More info

  A new microscope is discussed, where the scanning illumination has a numerical aperture of 2.8 with lambda = 1.56 mu m femtosecond fiber laser. Samples are placed or grown on a silicon substrate. Multi-photon emission is imaged in transmission on a cooled CCD. Two-photon and three-photon effects are observed from the silicon/water interface and gold nanoparticles. Images of cells, reference spheres and gold nanoparticles illustrate imaging properties of the microscope. Spectral characteristics of individual particles are achieved with a blazed transmission grating. Emission properties of differently sized gold nanoparticles are studied in detail, which indicate that their emission is a two-photon effect due continuum generation. Interestingly, spectral shape and emission power are similar for 20nm, 40nm and 60nm diameter gold nanoparticles for the cases studied. (C) 2013 Optical Society of America
• Wang, Q., Khanh, K., Honkanen, S., & Kueppers, F. (2008). Mode-locked fiber/waveguide lasers based on a fiber taper embedded in carbon nanotubes/polymer composite. Proceedings of SPIE - The International Society for Optical Engineering, 6996.
  More info

  Abstract: We generated 2 nJ, ∼690 fs pulses with 10 MHz repetition rate from a linear cavity mode-locked Er3+-doped fiber laser with a fiber taper embedded in carbon nanotubes (CNTs)/polymer composite. Evanescent field out of the taper section can interact with CNTs to see saturation of absorption. With the fiber based saturable absorber this laser has simple and robust all-fiber configuration comparing to traditional linear cavity mode-locked lasers with semiconductor saturable absorbers. In addition, we have demonstrated a mode-locked ring laser, with a similar saturable absorber, by using an ion-exchanged Er3+-Yb3+-codoped planar waveguide as the gain medium.
• Wise, F. W., Ouzounov, D., Kieu, K., Renninger, W., Chong, A., & Liu, H. (2008). Advances in fiber lasers for nonlinear microscopy. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 6860.
  More info

  Abstract: Advances that will enable the demonstration of fiber lasers for nonlinear microscopy will be described, with a focus on the parameters appropriate to CARS microscopy.
• Kieu, K., & Mansuripur, M. (2007). Femtosecond laser pulse generation with a fiber taper embedded in carbon nanotube/polymer composite. Optics Letters, 32(15), 2242-2244.
  More info

  PMID: 17671597;Abstract: 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. © 2007 Optical Society of America.
• Kieu, K., & Mansuripur, M. (2007). Fiber laser using a microsphere resonator as a feedback element. OPTICS LETTERS, 32(3), 244-246.
  More info

  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 similar to 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. (c) 2007 Optical Society of America.
• Kieu, K., & Mansuripur, M. (2007). Fiber laser using a microsphere resonator as a feedback element. Optics Letters, 32(3), 244-246.
  More info

  PMID: 17215933;Abstract: 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 -108), 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. © 2007 Optical Society of America.
• Kieu, K., & Mansuripur, M. (2007). Micro-sphere resonator reflector for fiber laser. Proceedings of SPIE - The International Society for Optical Engineering, 6452.
  More info

  Abstract: We show that a glass micro-sphere resonator can be used as a wavelength-selective mirror in fiber lasers. Due to their high quality-factor (Q ∼108), microsphere resonators possess a narrow reflection bandwidth. This feature enables construction of single-frequency fiber lasers even when the cavity is long. We also propose and demonstrate an active Q-switched fiber laser using a high-Q micro-sphere resonator as the Q-switching element. The laser cavity consists of an Erdoped fiber as the gain medium, a glass micro-sphere 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 micro-sphere is modulated by changing the gap between the micro-sphere and the fiber taper. Active Q-switching is realized by oscillating the micro-sphere in and out of contact with the taper. Nonlinear effects (such as stimulated Raman lasing) were also observed in our setup at relatively low pump powers.
• Kieu, K., & Mansuripur, M. (2007). Self-locked excitation scheme for microsphere resonators. IEEE PHOTONICS TECHNOLOGY LETTERS, 19(2-4), 100-102.
  More info

  We propose a new scheme for exciting a resonant mode of a glass microsphere resonator. The concept is based on unique properties of coupled resonators. In the proposed setup, the microsphere plays the role of a feedback mirror in an erbium-doped fiber laser, where the lasing wavelength is automatically locked to a resonant mode of the microsphere. As a result, the laser radiation builds up to very high intensities inside the microsphere. Using a (multimode) pump diode laser at relatively low pump power, we achieve continuous-wave stimulated Raman lasing and generation of new laser frequencies by four-wave mixing.
• Kieu, K., & Mansuripur, M. (2007). Self-locked excitation scheme for microsphere resonators. IEEE Photonics Technology Letters, 19(2), 100-102.
  More info

  Abstract: We propose a new scheme for exciting a resonant mode of a glass microsphere resonator. The concept is based on unique properties of coupled resonators. In the proposed setup, the microsphere plays the role of a feedback mirror in an erbium-doped fiber laser, where the lasing wavelength is automatically locked to a resonant mode of the microsphere. As a result, the laser radiation builds up to very high intensities inside the microsphere. Using a (multimode) pump diode laser at relatively low pump power, we achieve continuous-wave stimulated Raman lasing and generation of new laser frequencies by four-wave mixing. © 2007 IEEE.
• Kim, C., Jung, K., Kieu, K., & Kim, J. (2007). Low timing jitter and intensity noise from a soliton Er-fiber laser mode-locked by a fiber taper carbon nanotube saturable absorber. OPTICS EXPRESS, 20(28), 29524-29530.
  More info

  We characterize the timing jitter and intensity noise of an 80-MHz soliton Er-fiber laser mode-locked by a fiber taper carbon nanotube saturable absorber (ft-CNT-SA) up to the Nyquist frequency. The measured rms timing jitter is 3.0 fs (11.0 fs) integrated from 10 kHz (1 kHz) to 40 MHz offset frequency. The measured rms relative intensity noise (RIN) is 0.069% (0.021%) integrated from 10 Hz to 40 MHz (1 MHz) offset frequency. We identify that the resulting timing jitter is dominated by the Gordon-Haus jitter originated from the negative dispersion necessary for soliton mode-locking with a slow saturable absorber. (C) 2012 Optical Society of America
• Lefrancois, S., Kieu, K., Deng, Y., Kafka, J. D., & Wise, F. W. (2007). Scaling of dissipative soliton fiber lasers to megawatt peak powers by use of large-area photonic crystal fiber. OPTICS LETTERS, 35(10), 1569-1571.
  More info

  We report an all-normal dispersion femtosecond laser based on large-mode-area Yb-doped photonic crystal fiber. Self-starting mode-locked pulses are obtained with an average power of 12 W at 84 MHz repetition rate, corresponding to 140 nJ of chirped pulse energy. These are dechirped to a near transform-limited duration of 115 fs. Experimental results are consistent with numerical simulations of dissipative soliton intra-cavity pulse evolution, and demonstrate scaling of 100 fs pulses to megawatt peak powers. (C) 2010 Optical Society of America
• Nguyen, T. N., Kieu, K., Maslov, A. V., Miyawaki, M., & Peyghambarian, N. (2007). Normal dispersion femtosecond fiber optical parametric oscillator. OPTICS LETTERS, 38(18), 3616-3619.
  More info

  We propose and demonstrate a synchronously pumped fiber optical parametric oscillator (FOPO) operating in the normal dispersion regime. The FOPO generates chirped pulses at the output, allowing significant pulse energy scaling potential without pulse breaking. The output average power of the FOPO at 1600 nm was similar to 60 mW (corresponding to 1.45 nJ pulse energy and similar to 55% slope power conversion efficiency). The output pulses directly from the FOPO were highly chirped (similar to 3 ps duration), and they could be compressed outside of the cavity to 180 fs by using a standard optical fiber compressor. Detailed numerical simulation was also performed to understand the pulse evolution dynamics around the laser cavity. We believe that the proposed design concept is useful for scaling up the pulse energy in the FOPO using different pumping wavelengths. (C) 2013 Optical Society of America
• Veiko, V. P., & Kieu, K. K. (2007). Laser amorphisation of glass ceramics: Basic properties and new possibilities for manufacturing microoptical elements. Quantum Electronics, 37(1), 92-98.
  More info

  Abstract: The laser amorphisation of glass ceramics (LAGC) is studied by optical pyrometry and video recording. The mechanism of local LAGC as a structural phase transition determined by the temperature kinetics in the laser-irradiated region is proposed. The ranges of the power density and exposures to the 10.6-μm IR radiation required for amorphisation of the typical glass ceramics, a SiO2- Al2O3-CaO-MgO-TiO2 sital are determined. It is shown that LAGC can be used to fabricate a number of miniature optical elements such as lenses, lens rasters, light guides and waveguides, etc. © 2007 Kvantovaya Elektronika and Turpion Ltd.
• Veiko, V. P., Kieu, Q. K., Novikov, B., Shakhno, E. A., & Yakovlev, E. B. (2007). Physical mechanisms of fast structure modification of glass-ceramics under CO₂-laser action. Proceedings of SPIE - The International Society for Optical Engineering, 6458.
  More info

  Abstract: Structure modification of glass-ceramics under laser action is a popular object of last years' research. This process has been shown to have some important peculiarities: very high rate and non-traditional kinetic. These peculiarities are explained in this paper based on thermophysical kinetic analysis and an unconventional consideration of amorphous material as a crystal deformed by vacancies (CDV).
• Fang, Q., Kieu, K., & Peyghambarian, N. (2006). An All-Fiber 2-mu m Wavelength-Tunable Mode-Locked Laser. IEEE PHOTONICS TECHNOLOGY LETTERS, 22(22), 1656-1658.
  More info

  We report an all-fiber thulium-doped wavelength-tunable mode-locked laser operating near 2 mu m. Reliable self-starting mode locking over a large tuning range (>50 nm) using a fiber-taper-based carbon nanotube saturable absorber is observed. Spectral tuning is achieved by stretching another fiber taper. To the best of our knowledge, this is the first demonstration of an all-fiber wavelength tunable mode-locked laser near 2 mu m.
• Fang, Q., Shi, W., Kieu, K., Petersen, E., Chavez-Pirson, A., & Peyghambarian, N. (2006). High power and high energy monolithic single frequency 2 mu m nanosecond pulsed fiber laser by using large core Tm-doped germanate fibers: experiment and modeling. OPTICS EXPRESS, 20(15), 16410-16420.
  More info

  We report a high power and high energy all-fiber-based single frequency nanosecond pulsed laser source at similar to 1918.4 nm in master oscillator-power amplifier (MOPA) configuration. The pre-shaped pulsed fiber laser seed with a variable pulse duration and repetition rate were achieved by directly modulating a continuous wave (CW) single frequency fiber laser using a fast electro-optical modulator (EOM) driven by a arbitrary waveform generator (AWG). One piece of single mode, large (30 mu m) core, polarization-maintaining (PM) highly thulium-doped (Tm-doped) germanate glass fiber (LC-TGF) was used to boost the pulse power and pulse energy of these modulated pulses in the final power amplifier. To the best of our knowledge, the highest average power 16 W for single frequency transform-limited similar to 2.0 ns pulses at 500 kHz was achieved, and the highest peak power 78.1 kW was achieved at 100 kHz. Furthermore, mJ pulse energy was achieved for similar to 15 ns pulses at 1 kHz repetition rate. Theoretical modeling of the large-core highly Tm-doped germanate glass double-cladding fiber amplifier (LC-TG-DC-FA) is also present for 2 mu m nanosecond pulse amplification. A good agreement between the theoretical and experimental results was achieved. The model was also utilized to investigate the dependence of the stored energy in the LC-TGF on the pump power, seed energy and repetition rate, which can be used to design and optimize the LC-TG-DC-FA to achieve higher pulse energy. (C) 2012 Optical Society of America
• Karvonen, L., Saynatjoki, A., Chen, Y., Jussila, H., Ronn, J., Ruoho, M., Alasaarela, T., Kujala, S., Norwood, R. A., Peyghambarian, N., Kieu, K., & Honkanen, S. (2006). Enhancement of the third-order optical nonlinearity in ZnO/Al2O3 nanolaminates fabricated by atomic layer deposition. APPLIED PHYSICS LETTERS, 103(3).
  More info

  We investigate the third-order optical nonlinearity in ZnO/Al2O3 nanolaminates fabricated by atomic layer deposition and show that the third-order optical nonlinearity can be enhanced by nanoscale engineering of the thin film structure. The grain size of the polycrystalline ZnO film is controlled by varying the thickness of the ZnO layers in the nanolaminate in which thin (similar to 2 nm) amorphous Al2O3 layers work as stopping layers for ZnO crystal growth. Nanoscale engineering enables us to achieve a third harmonic generated signal enhancement of similar to 13 times from the optimized nanolaminate structure compared to a ZnO reference film of comparable thickness. (C) 2013 AIP Publishing LLC.
• Kieu, K. Q., & Mansuripur, M. (2006). Biconical fiber taper sensors. IEEE PHOTONICS TECHNOLOGY LETTERS, 18(21-24), 2239-2241.
  More info

  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 Delta T similar to 1 degrees C, and a refractive-index sensor capable of measuring Delta n similar to 1.42 x 10(-5) are demonstrated using tapers made from a standard single-mode fiber.
• Kieu, K. Q., & Mansuripur, M. (2006). Biconical fiber taper sensors. IEEE Photonics Technology Letters, 18(21), 2239-2241.
  More info

  Abstract: 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 ΔT ∼ 1 °C, and a refractive-index sensor capable of measuring Δn ∼ 1 1.42 × 10-5 are demonstrated using tapers made from a standard single-mode fiber. © 2006 IEEE.
• Kieu, K., & Mansuripur, M. (2006). Active Q switching of a fiber laser with a microsphere resonator. Optics Letters, 31(24), 3568-3570.
  More info

  PMID: 17130905;Abstract: 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 ∼102 W, duration ∼160ns) at a low pump-power threshold (∼3 mW). © 2006 Optical Society of America.
• Kieu, K., & Mansuripur, M. (2006). Tuning of fiber lasers by use of a single-mode biconic fiber taper. Optics Letters, 31(16), 2435-2437.
  More info

  PMID: 16880847;Abstract: 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. © 2006 Optical Society of America.
• Kieu, K., Churin, D., Schneebeli, L., Norwood, R. A., & Peyghambarian, N. (2006). Brillouin lasing in integrated liquid-core optical fibers. OPTICS LETTERS, 38(4), 543-545.
  More info

  We report Brillouin lasing in an integrated liquid-core optical fiber filled with neat CS2. This is the first observation of Brillouin lasing in an optical fiber filled with a liquid, to the best of our knowledge. The linewidth of the single frequency liquid-based Brillouin laser was estimated to be
• 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), 7826-7831.
  More info

  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 similar to 200 pulses for full crystallization, for the GeBiTe samples approximately 15 pulses sufficed. (c) 2006 Optical Society of America.
• 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), 7826-7831.
  More info

  PMID: 17068516;Abstract: 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 -200 pulses for full crystallization, for the GeBiTe samples approximately 15 pulses sufficed. © 2006 Optical Society of America.
• Kieu, K., Narumi, K., & Mansuripur, M. (2006). Investigation of crystallization and amorphization dynamics of phase-change thin films using sub-nanosecond laser pulses. Proceedings of SPIE - The International Society for Optical Engineering, 6282.
  More info

  Abstract: 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 follows 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 multi-pulse 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 ~200 pulses for full crystallization, for GeBiTe samples approximately 15 pulses sufficed.
• Mansuripur, M., & Kieu, K. (2006). Subnanosecond pulsed laser studies of phase-change recording media. 2006 Optical Data Storage Topical Meeting - Post Deadline Papers, 126-128.
  More info

  Abstract: We report the observed behavior of various phase-change (PC) samples under short-pulse laser irradiation. A pump-and-probe technique is used to elucidate the dynamics of melting and amorphization, as well as the mechanism of multi-pulse crystallization. We also obtain estimates of the thermal constants of the PC layer as well as those of the adjacent layers. © 2006 IEEE.
• Veiko, V. P., Kieu, Q. K., Nikonorov, N. V., Shur, V., Luches, A., & Rho, S. (2005). Laser-induced modification of glass-ceramics microstructure and applications. Applied Surface Science, 248(1-4), 231-237.
  More info

  Abstract: The laser-induced modifications in two kinds of glass-ceramics (GCs) with composition TiO2-SiO2 (Sitall ST-50) and Li 2O-SiO2 (Fotoform) were investigated for fabricating optical elements. The laser-induced change of refractive index and surface relief constituted the first step of this task. The second stage was a chemical processing including ion exchange (Li ↔ Na, K, Rb, for "Fotoform" GCs) and etching of irradiated and non-irradiated areas. As a result of the above-mentioned processes, mini- and micro-optical components based on two GCs have been fabricated: lenses and lens arrays, waveguides and other waveguiding components, diffractive gratings, etc. © 2005 Elsevier B.V. All rights reserved.
• Kieu, Q. K., & Veiko, V. P. (2004). Laser fabrication of optical microspheres. Proceedings of SPIE - The International Society for Optical Engineering, 5399, 126-132.
  More info

  Abstract: A new method for fabrication of optical microspheres with the use of a CW CO2 laser is reported. Conventional method for fabrication of microspheres includes grinding and polishing processes which is not only time consuming, but also difficult of getting optical spheres with diameter less than 500 μm. It will be demonstrated that the laser method is very simple and capable of producing a wide range of optical spheres with diameter of several millimeters down to 10 micrometers or even less, and a wide range of materials can be used (glasses, porous glasses, glass-like ceramics...). Some applications of microspheres produced by the laser method are discussed.
• Kieu, Q. K., & Veiko, V. P. (2004). Spherical mcrocavity resonator fabrication based on laser technology. Proceedings of SPIE - The International Society for Optical Engineering, 5662, 141-148.
  More info

  Abstract: We discuss our recent experiments that aim at fabrication of optical microsphere resonators and methods for their quality estimation. First, free space laser melting technique (FSLMT) was investigated. Different regimes of laser action and its corresponding results were discussed. Secondly, we fabricated optical microsphere resonators of different sizes and optical glasses (including active glasses) using FSLMT. Whispering gallery modes (WGMs) in fabricated microsphere resonators were then observed in microspheres' fluorescence spectrums, the free spectral ranges were in good agreement with diameters of microspheres. Furthermore, WGMs of microsphere resonators were excited by an optical fiber-taper coupler to assess the microspheres' Q-factor. Applications of optical microsphere resonators such as microlaser, simple block for studying emission and nonlinear optical effects were demonstrated.
• Veiko, V. P., & Kieu, Q. K. (2004). Phase-structure transformations of glass-ceramics under laser heating as a way to create new microoptical components and materials. Proceedings of SPIE - The International Society for Optical Engineering, 5399, 11-20.
  More info

  Abstract: Laser amorphization of glass-ceramics (LAGC) is investigated by optical pyrometry and video recording. Due to this new knowledge, the mechanism of local LAGC is made clear as a phenomenon leaded by thermal kinetic. The required power density and temporal range of CO2-laser irradiation for amorphization of a typical glass-ceramic (GC) α-TiO2 · 2MgO 2Al2O3 · 5SiO2 are defined. Fabrication of a wide range of microoptical components such as lenses, lens arrays, wave-guides, geodesic lenses... are demonstrated with methods for controlling of their parameters.
• Veiko, V. P., Kieu, Q. K., & Nikonorov, N. V. (2004). Laser modification of glass-ceramics structure and properties: A new view to traditional materials. Proceedings of SPIE - The International Society for Optical Engineering, 5662, 119-128.
  More info

  Abstract: Glass-ceramics (GCs) usually have glass structure doped with microcrystalls that are responsible for main properties: mechanical, chemical, optical etc. As for optical properties, GCs are non-optical materials due to a strong scattering in the visible range. By now different laser technologies for modification of structure of GCs structure have been developed. Heating of GCs with the use of a laser radiation transforms crystalline phase in to glassy. It results in a change of following physical and chemical properties of the irradiated area as density, volume, viscosity, hardness, transparency, refraction, etc. The most important thing is that optical transparency of GCs drastically increases in the visible and near IR range due to the appearance of a new glassy structure. Variation of laser treatment conditions (power, exposure, wavelength from IR to UV) as well as selection of composition of GCs allows to control mentioned characteristics. We have investigated two compositions of GCs with crystalline phases of TiO2-SiO2 (Sitall ST-50) and Li2O-SiO2 ("Fotoform"). The change of refractive index and surface relief has been used as the first step for fabrication of optical elements. The second stage was a chemical processing including an ion exchange technique (Li ↔ Na, K, Rb, for "Fotoform") and etching of irradiated and non-irradiated areas. Crystalline and glassy phases have different diffusion coefficient and rates of etching. It allows to modify the refractive index and the surface relief of optical elements.. The other important feature is a difference in the macroscopic volumes of ordered-disordered phases which can be used to produce some surface reliefs etc. As a result of above mentioned research mini- and micro-optical components based on two GCs have been fabricated and demonstrated: lenses and lens arrays, waveguides and other waveguiding components, difractive gratings, integrated diaphragms etc.
• Veiko, V. P., Kieu, Q. K., & Nikonorov, N. V. (2004). Laser modification of structure and properties of glass-ceramics. Proceedings of SPIE - The International Society for Optical Engineering, 5339, 250-257.
  More info

  Abstract: There are many phenomena that occur during laser radiation interaction with solids, one of them is hardening. In a broad sense of this word, it is a way to keep or to "froze" the high temperature structure of materials after being melted. Maybe the case of glass-ceramics laser hardening is one of the most impressive. Because the high temperature structure induced by laser radiation acting on these materials is mostly amorphous (the structure consists of 70-80% or even more glass phase) - keeping this structure means to save at room temperature optical properties of appeared glass, first of all-transmission, dispersion and very often optical force. Many aspects of the mentioned phenomenon were discussed in previous papers qualitatively 1, 2, 3. In this paper we present quantitative data about rates of heating-cooling and corresponding changes in typical glass-ceramics such as cracking, amorphization, and reverse crystallization. The next aim of the paper is to illustrate changes in structural, chemical, mechanical, and optical properties due to laser radiation interaction with glass-ceramics. Thus, we demonstrated a way how to develop new materials with the use of laser modification of glass-ceramics.
• Veiko, V. P., Kieu, Q. K., & Skiba, P. K. (2003). Laser amorphisation of glass-ceramics (LAGS) laws and new possibility to form a number of microoptical components. Proceedings of SPIE - The International Society for Optical Engineering, 5063, 137-144.
  More info

  Abstract: Laser amorphization of glass-ceramics (LAGC) is investigated by optical pyrometry and video recording. Due to this new knowledge, the mechanism of local LAGC is made clear as a phenomenon leaded by thermal kinetic. The required power density and temporal range of CO2-laser irradiation for amorphization of a typical glass-ceramic (GC) α-TiO2 2MgO · 2Al2O3 · 5SiO2 is defined. It is demonstrated that a wide range of miniature optical components such as lenses, lenslet arrays, waveguides, geodesic (plane) lenses, etc...can be fabricated by LAGC.

Proceedings Publications

• Kieu, K. Q. (2014, February). Normal dispersion femtosecond fiber optical parametric oscillator. In Photonics West 2014.
• Kieu, K. Q. (2014, July). Multiphoton Microscopy Characterization of Plasmonic Enhanced Nanodevices. In Integrated Photonics Research, Silicon and Nanophotonics.
• Kieu, K. Q. (2014, July). THG as a probe for photodegradation analysis of EO polymers. In Integrated Photonics Research, Silicon and Nanophotonics.
• Kieu, K. Q. (2014, May). Polymethines with macroscopic optical nonlinearities suitable for all-optical signal processing. In CLEO 2014.
  More info

  By preventing aggregation of polymethine molecules at high number density, we have developed organic materials with large third-order nonlinearities and low nonlinear absorption in the near-infrared thereby enabling demonstration of an all-optical signal processing application.
• Kieu, K. Q. (2014, May). Timing Jitter Minimization in Soliton Mode-Locked Fiber Lasers by Dispersion Engineering. In CLEO 2014.
• Kieu, K. Q. (2014, May). Widely tunable normal dispersion fiber optical parametric oscillator. In CLEO 2014.
  More info

  We demonstrate a very wide tuning range normal dispersion fiber optical parametric oscillator (FOPO) using a femtosecond, fixed wavelength fiber laser as the pump source. A tuning range from 1360nm to 1835nm with pulse energy up to 1.3 nJ was achieved by operating the FOPO in the normal dispersion regime. We believe that the proposed laser design will be useful for developing widely tunable and high energy ultrafast fiber laser sources.
• Kieu, K. Q. (2014, November). Investigation of optical nonlinearities in graphene and layered semiconductors by multiphoton imaging. In 8th Energy Materials Nanotechnology (EMN) Fall Meeting.
• Kieu, K. Q. (2014, October). Difference frequency generation at 9µm wavelength using a compact all-fiber laser source based on Thulium and Erbium fiber amplifiers. In Frontier in Optics 2014.
  More info

  We demonstrate a mid-infrared frequency comb spanning from 7.5 to 11.6µm using difference frequency generation in a AgGaS2 crystal with a compact all-fiber source based on Tm and Er-amplifiers.
• Kieu, K., Narumi, K., Mansuripur, M., Katayama, R., & Schlesinger, T. (2013). Investigation of crystallization and amorphization dynamics of phase-change thin films using sub-nanosecond laser pulses - art. no. 62820J. In Optical Data Storage 2006, 6282, J2820-J2820.
  More info

  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 follows 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 multi-pulse 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 similar to 200 pulses for full crystallization, for GeBiTe samples approximately 15 pulses sufficed.
• Kieu, K., Peyghambarian, N., Periasamy, A., Konig, K., & So, P. (2013). Synchronized picosecond pulses at two different wavelengths from a compact fiber laser source for Raman microscopy. In MULTIPHOTON MICROSCOPY IN THE BIOMEDICAL SCIENCES XI, 7903.
  More info

  We report on the development of a fiber laser system that supplies synchronized picosecond pulses at two different wavelengths suitable for Raman microscopy.
• Kieu, K., Wise, F. W., & , . (2013). Self-similar and Stretched-pulse Operation of Erbium-doped Fiber Lasers with Carbon Nanotubes Saturable Absorber. In 2009 CONFERENCE ON LASERS AND ELECTRO-OPTICS AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2009), VOLS 1-5, 536-537.
  More info

  We report self-similar and stretched-pulse operations in an all-fiber erbium-doped laser using carbon nanotube saturable absorber, for the first time. Pulses as short as 115fs are achieved in the stretched-pulse regime. (C) 2008 Optical Society of America
• Liu, G., Kieu, K., Wise, F. W., Chen, Z., Periasamy, A., So, P., & Konig, K. (2013). Fiber-based multiphoton system. In MULTIPHOTON MICROSCOPY IN THE BIOMEDICAL SCIENCES X, 7569.
  More info

  A fiber based multiphoton microscopy (MPM) system is designed and demonstrated. An all normal dispersion fiber laser with central wavelength around 1um was used as laser source. A double clad photonic crystal fiber (DCPCF), and galvanometer mirror scanner based handheld probe is designed. Second harmonic generation (SHG) images and two photon excited fluorescence (TPEF) images of biological tissue were demonstrated by the system.
• Wise, F. W., Kieu, K., Saar, B., Holtom, G., Xie, S., Periasamy, A., & So, P. (2013). Fiber lasers for CARS microscopy. In MULTIPHOTON MICROSCOPY IN THE BIOMEDICAL SCIENCES IX, 7183.
  More info

  We report a fiber-based high-power picosecond laser system for coherent Raman microscopy (CRM). This source generates 3-ps pulses with 6 W average power at 1030 nm. Frequency-doubling yields more than 2 W of green light, which can be used to pump a commercial optical parametric oscillator to produce the pump and Stokes beams for CRM. The design and performance of the laser are described, along with an application to CARS imaging.
• Wise, F. W., Ouzounov, D., Kieu, K., Renninger, W., Chong, A., Liu, H., Periasamy, A., & So, P. (2013). Advances in fiber lasers for nonlinear microscopy. In MULTIPHOTON MICROSCOPY IN THE BIOMEDICAL SCIENCES VIII, 6860.
  More info

  Advances that will enable the demonstration of fiber lasers for nonlinear microscopy will be described, with a focus on the parameters appropriate to CARS microscopy.
• Himmelhuber, R., Khanh Kieu, ., Herrera, O. D., Norwood, R. A., Peyghambarian, N., & , . (2012). Characterization of coplanar poled electro optic polymer films for Si-photonic devices with multiphoton microscopy. In 2013 IEEE OPTICAL INTERCONNECTS CONFERENCE, 90-91.
• Karvonen, L., Alasaarela, T., Jussila, H., Mehravar, S., Chen, Y., Saynatjoki, A., Norwood, R. A., Peyghambarian, N., Kieu, K., Honkanen, S., Lipsanen, H., Digonnet, M., & Jiang, S. (2012). Nanolaminate structures fabricated by ALD for reducing propagation losses and enhancing the third-order optical nonlinearities. In OPTICAL COMPONENTS AND MATERIALS XI, 8982.
  More info

  We demonstrate a novel atomic layer deposition (ALD) process to make high quality nanocrystalline titanium dioxide (TiO2) and zinc oxide (ZnO) with intermediate Al2O3 layers to limit the crystal size. The waveguide losses of TiO2/Al2O3 nanolaminates measured using the prism coupling method for both 633 nm and 1551 nm wavelengths are as low as 0.2 +/- 0.1 dB/mm with the smallest crystal size. We also show that the third-order optical nonlinearity in ZnO/Al2O3 nanolaminates can be enhanced by nanoscale engineering of the thin film structure.
• Kieu, K., Churin, D., Norwood, R. A., Peyghambarian, N., & , . (2012). Brillouin lasing in integrated liquid-core optical fibers. In 2012 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO).
  More info

  We report Brillouin lasing in an integrated liquid-core optical fiber (i-LCOF) filled with neat CS2. This is the first observation of Brillouin lasing in the liquid state of matter, to the best of our knowledge. The linewidth of the single frequency liquid-based Brillouin laser was estimated to be < 1kHz by beating two similar but independent lasers. (c) 2012 Optical Society of America
• Kieu, K., Klein, J., Evans, A., Barton, J., Peyghambarian, N., & , . (2012). Ultrahigh resolution all-reflective OCT system with a compact fiber-based supercontinuum source. In 2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO).
  More info

  We report the construction and characterization of an all-reflective OCT (R-OCT) system using a newly developed compact fiber-based broadband supercontinuum source. We achieved an axial resolution of 1.5 mu m in tissue (2 mu m in air) with 87 dB dynamic range at a center wavelength around 1300 nm. (C) 2010 Optical Society of America
• Kieu, K., Wu, T., Peyghambarian, N., Jones, R. J., & , . (2012). All-fiber carbon nanotube based mode-locked laser system for generation of stable fs frequency combs. In 2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS).
  More info

  We report on a simplified all-fiber octave spanning femtosecond laser system based on a tapered fiber carbon nanotube saturable absorber capable of generating a stabilized frequency comb structure. (C)2009 Optical Society of America
• Mansuripur, M., Kieu, K., & , . (2012). Subnanosecond pulsed laser studies of phase-change recording media. In 2006 Optical Data Storage Topical Meeting, Conference Proceedings, 126-128.
  More info

  We report the observed behavior of various phase-change (PC) samples under short-pulse laser irradiation. A pump-and-probe technique is used to elucidate the dynamics of melting and amorphization, as well as the mechanism of multi-pulse crystallization. We also obtain estimates of the thermal constants of the PC layer as well as those of the adjacent layers.
• Tada, K., Cohoon, G., Kieu, K., Mansuripur, M., & Norwood, R. A. (2012, May). Fabrication of High-Q Microresonators using Femtosecond Laser Micromachining. In 2012 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO).
  More info

  We report a novel technique to fabricate microdisk resonators using femtosecond laser micromachining. The resonators had suppressed higher order modes with a measured Q-factor as high as 7.8. x 10(6).
• Bale, B. G., Kieu, K., Wise, F., Kutz, J. N., Tankala, K., & Dawson, J. (2011). Characterizing the transition dynamics for multi-pulsing in mode-locked lasers. In FIBER LASERS VII: TECHNOLOGY, SYSTEMS, AND APPLICATIONS, 7580.
  More info

  We consider experimentally and theoretically a refined parameter space near the transition to multi-pulse mode-locking. Near the transition, the onset of instability is initiated by a Hopf (periodic) bifurcation. As cavity energy is increased, the band of unstable, oscillatory modes generates a chaotic behavior between single-and multi-pulse operation. Both theory and experiment are in good qualitative agreement and they suggest that the phenomenon is of a universal nature in mode-locked lasers at the onset of multi-pulsing from N to N + 1 pulses per round trip. This is the first theoretical and experimental characterization of the transition behavior, made possible by a highly refined tuning of the gain pump level.
• Cohoon, G. A., Kieu, K., Norwood, R. A., Kudryashov, A., Paxton, A., Ilchenko, V., Aschke, L., & Washio, K. (2011). Multiphoton excitation of organic chromophores in microbubble resonator. In LASER RESONATORS, MICRORESONATORS, AND BEAM CONTROL XVI, 8960.
  More info

  We report the observation of multiphoton excitation of organic chromophores in microbubble whispering gallery mode resonators. High-Q microbubble resonators are a formed by heating a pressurized fused silica capillary to form a hollow bubble which can be filled with liquid. In this case, the microbubble is filled with a solution of Rhodamine 6G dye. The resonator and dye are excited by evanescently coupling CW light from a 980nm laser diode using a tapered optical fiber. The two-photon fluorescence of the dye can be seen with pump powers as low as 1 mW.
• Kieu, K., Jones, R. J., & Peyghambarian, N. (2011, May). High power femtosecond source near 1 micron based on an all-fiber Er-doped mode-locked laser. In 2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO).
  More info

  We report the design and performance of a high power femtosecond laser source near 1 micron wavelength which is generated from an octave-spanning supercontinuum (SC) pumped by an Er-doped mode-locked laser. (C) 2010 Optical Society of America
• Kieu, K., Merzlyak, Y., Schneebeli, L., Hales, J., Perry, J., Norwood, R. A., Peyghambarian, N., & , . (2011). Integrated liquid-core optical fibers for ultra-efficient nonlinear liquid photonics. In 2012 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO).
  More info

  We have developed a technique that allows splicing of liquid core optical fiber (LCOF) to standard fiber with low loss. As an example, we demonstrated ultralow threshold Raman generation in an integrated CS2 filled LCOF. (C) 2011 Optical Society of America
• Makarov, N. S., Lau, P. C., Kieu, K., Norwood, R. A., Peyghambarian, N., Perry, J. W., & , . (2011). Correlating one-photon, two-photon and excited state spectroscopy of CdSe quantum dots. In 2012 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO).
  More info

  We present two-photon absorption and excited-state absorption spectra of quantum dots of various sizes. From the linear and transient spectra we determine transition dipole moments between the states and compare them with the two-photon cross sections.
• Shahin, S., Kieu, K., Marder, S. R., Norwood, R. A., Peyghambarian, N., & , . (2011). SPM Spectral Broadening Compensation Using Organic Dyes with Negative n(2). In 2013 OPTICAL FIBER COMMUNICATION CONFERENCE AND EXPOSITION AND THE NATIONAL FIBER OPTIC ENGINEERS CONFERENCE (OFC/NFOEC).
  More info

  Spectral broadening caused by SPM degrades performance of light-wave, multichannel communication systems. We propose a novel method in LCOF to compensate the SPM spectral broadening in systems using different concentrations of negative n(2) organic dyes. (c) 2013 Optical Society of America
• Churin, D., Kieu, K., Peyghambarian, N., Honea, E., & Hendow, S. (2010). The role of the saturable absorber in a mode-locked fiber laser. In FIBER LASERS IX: TECHNOLOGY, SYSTEMS, AND APPLICATIONS, 8237.
  More info

  We experimentally investigated the role of the saturable absorber (SA) in a mode-locked fiber laser. It is shown that the modulation depth of the SA significantly affects the pulse duration at the laser output for a given cavity design (mainly cavity dispersion and nonlinearity).
• Kieu, K., Jones, J. R., Peyghambarian, N., & , . (2010). Generation of sub-20fs pulses from an all-fiber carbon nanotube mode-locked laser system. In 2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS).
  More info

  We report a simple all-fiber femtosecond laser system based on carbon nanotube saturable absorber that was capable of generating 17-fs pulses with optical spectrum extending from 1000 nm to 1750 nm. (C) 2009 Optical Society of America
• Kieu, K., Schneebeli, L., Hales, J. M., Perry, J. W., Norwood, R. A., Peyghambarian, N., & , . (2010). All-optical switching via inverse Raman scattering in an optical fiber. In 2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO).
  More info

  We report the observation of inverse Raman scattering (IRS) in optical fiber. The achieved level of attenuation via IRS in an optical fiber is > 20dB at a time scale < 5ps. We found good agreement between experimental data and theoretical calculations. (C)2010 Optical Society of America
• Ageev, E., Kieu, K., Veiko, V. P., Veiko, V., & Vartanyan, T. (2009). Modification of photosensitive glass-ceramic Foturan by ultra short laser pulses. In FUNDAMENTALS OF LASER-ASSISTED MICRO- AND NANOTECHNOLOGIES 2010, 7996.
  More info

  In this paper laser-induced modification of photosensitive glass-ceramic materials under YAG:Nd second harmonic picosecond pulses is observed. The method for such modification based on laser processing and subsequent heat treatment is developed. The comparison for infrared femtosecond modification is introduced.

Presentations

• Kieu, K. Q. (2014, February). Multiphoton excitation of organic chromophores in microbubble resonator. Photonics West 2014.
  More info

  We report the observation of multiphoton excitation of organic chromophores in microbubble whispering gallery mode resonators. High-Q microbubble resonators are a formed by heating a pressurized fused silica capillary to form a hollow bubble which can be filled with liquid. In this case, the microbubble is filled with a solution of Rhodamine 6G dye. The resonator and dye are excited by evanescently coupling CW light from a 980nm laser diode using a tapered optical fiber. The two-photon fluorescence of the dye can be seen with pump powers as low as 1 mW.
• Kieu, K. Q. (2014, February). Nanolaminate structures fabricated by ALD for reducing propagation losses and enhancing the third-order optical nonlinearities. Photonics West 2014.
  More info

  We demonstrate a novel atomic layer deposition (ALD) process to make high quality nanocrystalline titanium dioxide (TiO2) and zinc oxide (ZnO) with intermediate Al2O3 layers to limit the crystal size. The waveguide losses of TiO2/Al2O3 nanolaminates measured using the prism coupling method for both 633 nm and 1551 nm wavelengths are as low as 0.2 +/- 0.1 dB/mm with the smallest crystal size. We also show that the third-order optical nonlinearity in ZnO/Al2O3 nanolaminates can be enhanced by nanoscale engineering of the thin film structure.
• Kieu, K. Q. (2014, November). Ultrafast fiber lasers enabled by carbon nanotubes and their applications. 8th Energy Materials Nanotechnology (EMN) Fall Meeting.
• Kieu, K. Q. (2014, October). Mid-IR supercontinuum generation in an integrated liquid-core optical fiber filled with CS2. Frontier in Optics 2014.
• Kieu, K. Q. (2014, October). Multiphoton Imaging with Compact Femtosecond Fiber Lasers. Frontier in Optics 2014.
  More info

  We discuss the development of compact, affordable multiphoton microscopes using robust femtosecond fiber lasers as the excitation source. Application in brain imaging and Barrett's cancer imaging will be presented.
• Kieu, K. Q. (2014, September). Functional glass and applications in fiber lasers and fiber optics. 2014 The European Conference on Optical Communication (ECOC).
  More info

  Phosphate, telluride, and fluoride glasses allow new fiber laser frequencies. Some nonlinear effects including optical parametric oscillators (OPO), SRS and SBS extend the operating wavelengths while others like SBS prevent high power operation. Our recent advances will be summarized.

Others

• Richards, B. C., Hendrickson, J., Olitzky, J. D., Gibson, R., Gehl, M., Kieu, K., Khankhoje, U. K., Homyk, A., Scherer, A., Kim, J., Lee, Y., Khitrova, G., & Gibbs, H. M. (2010, APR 9). Characterization of 1D photonic crystal nanobeam cavities using curved microfiber (vol 18, pg 20558, 2010). OPTICS EXPRESS.
  More info

  An error was made in the calculation of the photonic crystal mode volume. Fixing this error increases our mode volumes by a factor of two and makes our claim of highest Q/V invalid. (C)2010 Optical Society of America