Prof. Ken-ichi Ueda Profile

Prof. Ken-ichi Ueda

Professor and Lab Director at Univ. of Electro Communications

SPIE Involvement:

Author

Publications (56)

Proceedings Article | 16 February 2012 Paper

High-power single-frequency photonic bandgap fiber amplifier at 1178 nm

Meishin Chen, Akira Shirakawa, Yoshiaki Yamahara, Ken-ichi Ueda, Christina Olausson, Jens Lyngsø, Jes Broeng

Proc. SPIE. 8237, Fiber Lasers IX: Technology, Systems, and Applications

KEYWORDS: Raman spectroscopy, Fiber amplifiers, Amplifiers, Acoustics, Optical amplifiers, Fiber lasers, Optical isolators, Laser scattering, Scattering, Ytterbium

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Proceedings Article | 17 February 2010 Paper

Power-scalable long-wavelength Yb-doped photonic bandgap fiber sources

Christina Olausson, Akira Shirakawa, Hiroki Maruyama, Ken-ichi Ueda, Jens Lyngsø, Jes Broeng

Proc. SPIE. 7580, Fiber Lasers VII: Technology, Systems, and Applications

KEYWORDS: Fiber amplifiers, Fiber lasers, Amplifiers, Ytterbium, Cladding, Second-harmonic generation, Harmonic generation, Semiconductor lasers, Laser applications, Raman spectroscopy

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Proceedings Article | 20 February 2007 Paper

Laser performance of Yb3+:YAG ceramic microchip lasers

Jun Dong, Akira Shirakawa, Ken-ichi Ueda, Hideki Yagi, Takagimi Yanagitani, Alexander Kaminskii

Proc. SPIE. 6451, Solid State Lasers XVI: Technology and Devices

KEYWORDS: Ceramics, YAG lasers, Chromium, Absorption, Ytterbium, Q switched lasers, Output couplers, Pulsed laser operation, Picosecond phenomena, Laser applications

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The optical properties of Yb:YAG ceramic doped with different Yb concentrations are presented. The absorption coefficient at peak absorption wavelength of 940 nm increases linearly with Yb concentration in Yb:YAG ceramics. Low-threshold and highly-efficient continuous-wave (cw) laser-diode end-pumped Yb:YAG microchip ceramic laser with near-diffraction-limited beam quality was demonstrated at room temperature. Slope efficiencies of 79%, 67% and optical-to-optical efficiency of 60%, 53% at 1030 nm and 1049 nm, respectively were achieved for 1-mm-thick Yb:YAG ceramic plate (C_Yb = 9.8 at.%) under cw laser-diode pumping. Dual-wavelength operation at 1030 nm and 1049 nm with 5% transmission of the output coupler was achieved by varying pump power intensity. 1049 nm laser operation was automatically obtained by using 5% transmission output coupler when absorbed pump power is higher than 1 W. The lasers operate in multi-longitudinal-mode; the effect of pump power on the laser emission spectra for both wavelengths is addressed. The laser wavelength around 1030 nm shifts to short wavelength at low pump power region and then to red with increase of the absorbed pump power, while the laser wavelength around 1049 nm does not change with the pump power. Excellent laser performance indicates Yb:YAG ceramic laser materials could be potentially used in high-power solid-state lasers operating at 1030 nm, 1049 nm, or both wavelengths simultaneously. Laser-diode pumped lowthreshold and highly-efficient passively Q-switched Yb:YAG ceramic microchip laser with Cr⁴⁺:YAG ceramic as saturable absorber has also been demonstrated. The slope efficiency is as high as 37%, and the optical-to-optical efficiency is as high as 29% for 89% initial transmission of Cr⁴⁺:YAG ceramic. The pulse width of 380 ps and peak power of over 82 kW at repetition rate of 12.4 kHz was obtained. Single-longitudinal-mode oscillation and wide-separated multi-longitudinal-mode oscillation due to etalon effect of Cr⁴⁺:YAG thin plate was achieved depending on the pump power level.

Proceedings Article | 8 September 2006 Paper

Switchable lasing of 1040- and 1537-nm lines based on the optical bistability in the pump-bypassed ytterbium-doped fiber laser

Jianlang Li, Mitsuru Musha, Akira Shirakawa, Ken-ichi Ueda

Proc. SPIE. 6310, Photonic Devices and Algorithms for Computing VIII

KEYWORDS: Fiber lasers, Bistability, Ytterbium, Absorption, Wavelength division multiplexing, Fiber Bragg gratings, Fiber optic communications, Fiber optics, Laser optics, Free space optics

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Proceedings Article | 8 June 2006 Paper

Generation of MeV proton with 30 mJ laser energy by optimizing focusing spot using deformable mirror

Takuya Nayuki, Takashi Fujii, Yuji Oishi, Kei Takano, Xiaofang Wang, Alexander Andreev, Koshichi Nemoto, Ken-ichi Ueda

Proc. SPIE. 6018, 5th International Workshop on Adaptive Optics for Industry and Medicine

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Proceedings Article | 5 December 2005 Paper

Antiphase states of sub-nanosecond Cr,Yb:YAG microchip self-Q-switched multimode laser

Jun Dong, Akira Shirakawa, Ken-ichi Ueda

Proc. SPIE. 6020, Optoelectronic Materials and Devices for Optical Communications

KEYWORDS: Absorption, Pulsed laser operation, Numerical simulations, Q switched lasers, Crystals, Hole burning spectroscopy, Semiconductor lasers, Chromium, Continuous wave operation, Laser crystals

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Proceedings Article | 22 April 2005 Paper

CW 7-W 900-nm-wide supercontinuum source by phosphosilicate fiber Raman laser and high-nonlinear fiber

Akira Shirakawa, Ken-ichi Ueda

Proc. SPIE. 5709, Fiber Lasers II: Technology, Systems, and Applications

KEYWORDS: Fiber lasers, Raman spectroscopy, Continuous wave operation, Supercontinuum generation, Absorption, Fiber Bragg gratings, Supercontinuum sources, Modulation, Four wave mixing

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Proceedings Article | 22 April 2005 Paper

Fiber laser coherent array for power scaling, bandwidth narrowing, and coherent beam direction control

Akira Shirakawa, Keigo Matsuo, Ken-ichi Ueda

Proc. SPIE. 5709, Fiber Lasers II: Technology, Systems, and Applications

KEYWORDS: Fiber lasers, Fiber couplers, Reflectivity, Beam controllers, Resonators, Fiber Bragg gratings, Wavelength division multiplexing, Laser resonators, Laser damage threshold, Electro optics

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Proceedings Article | 23 March 2005 Paper

Diode-pumped Yb:YLF chirped-pulse regenerative amplifier for high average power operation

Junji Kawanaka, Hajime Nishioka, Koichi Yamakawa, Ken-ichi Ueda

Proc. SPIE. 5777, XV International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers

KEYWORDS: Crystals, Laser crystals, Semiconductor lasers, Optical amplifiers, Pulsed laser operation, Copper, Sapphire lasers, Liquid crystals, Diodes, Liquids

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Proceedings Article | 23 March 2005 Paper

Novel cooling technique for operation of quasi four-level solid-state laser

Todor Petrov, K. Takaichi, Hitoki Yoneda, Akira Shirakawa, Ken-ichi Ueda, Nikola Sabotinov

Proc. SPIE. 5777, XV International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers

KEYWORDS: Nitrogen, Ceramics, Liquids, Helium, Solid state lasers, Femtosecond phenomena, Crystals, Argon, Absorption, Fiber optic gyroscopes

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Proceedings Article | 8 October 2004 Paper

Fiber laser coherent array for power scaling of single-mode fiber laser

Akira Shirakawa, Keigo Matsuo, Ken-ichi Ueda

Proc. SPIE. 5662, Fifth International Symposium on Laser Precision Microfabrication

KEYWORDS: Fiber lasers, Fiber couplers, Beam controllers, Reflectivity, Resonators, Laser resonators, Single mode fibers, Fiber Bragg gratings, Laser applications, Laser processing

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Proceedings Article | 15 September 2004 Paper

Random lasing in Nd:YAG nano-crystalline-powder pumped by laser diode

Yan Feng, Jianren Lu, Shenghong Wang, Ken-ichi Ueda

Proc. SPIE. 5450, Photonic Crystal Materials and Nanostructures

KEYWORDS: Random lasers, Mirrors, Nd:YAG lasers, Neodymium, Semiconductor lasers, Backscatter, Laser damage threshold, Laser scattering, Scattering, Coating

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Proceedings Article | 7 April 2004 Paper

Measurements of nonlinear refractive indices in ceramic laser media

Yuri Senatsky, Akira Shirakawa, Y. Sato, J. Hagiwara, Jianren Lu, Kichi Ueda, H. Yagi, T. Yanagitani

Proc. SPIE. 5478, Laser Optics 2003: Solid State Lasers and Nonlinear Frequency Conversion

KEYWORDS: Ceramics, Laser applications, Refractive index, Crystals, Laser crystals, Nonlinear crystals, Laser development, High power lasers, Pulsed laser operation, Laser spectroscopy

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Proceedings Article | 10 November 2003 Paper

20-mJ diode-pumped chirped-pulse regenerative amplifier with a cooled Yb:LiYF4

Junji Kawanaka, Hajime Nishioka, Koichi Yamakawa, K. Ueda

Proc. SPIE. 5120, XIV International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers

KEYWORDS: Crystals, Optical amplifiers, Laser crystals, Semiconductor lasers, Mirrors, Laser systems engineering, Laser development, Sapphire lasers, High power lasers, Reflectors

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Proceedings Article | 6 October 2003 Paper

Raman fiber laser-pumped 2-um fiber laser

Atsushi Taniguchi, Tetsuro Kuwayama, Akira Shirakawa, Mitsuru Musha, Ken-ichi Ueda, Mahendra Prabhu

Proc. SPIE. 5137, International Conference on Lasers, Applications, and Technologies 2002: Advanced Lasers and Systems

KEYWORDS: Fiber lasers, Optical fibers, Ions, Wavelength division multiplexing, Fiber couplers, Raman spectroscopy, Single mode fibers, Fiber Bragg gratings, Absorption, Neodymium

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SPIE Journal Paper | 1 September 2003

Influence of cross-sectional shape on absorption characteristics of double-clad fiber lasers

Jianqiu Xu, Junhua Lu, Jianren Lu, Ken-ichi Ueda

OE Vol. 42 Issue 09

KEYWORDS: Absorption, Cladding, Fiber lasers, Wave propagation, Optical engineering, Lutetium, 3D modeling, Refractive index, Differential equations, Chemical elements

Proceedings Article | 19 February 2003 Paper

Study of optical properties of ultrashort-pulse laser-heated material

Hitoki Yoneda, Satoru Ohta, Ken-ichi Ueda, Richard More

Proc. SPIE. 4830, Third International Symposium on Laser Precision Microfabrication

KEYWORDS: Reflectivity, Laser beam diagnostics, Aluminum, Plasmas, Optical properties, Data modeling, Solids, Absorption, Pulsed laser operation, Skin

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Proceedings Article | 5 September 2002 Paper

Diode-pumped Yb:Y2O3 ceramic laser

Jian Kong, Ding Tang, Deyuan Shen, Jianren Lu, K. Takaichi, T. Uematsu, Ken-ichi Ueda, Hideki Yagi, T. Yanagitani, Alexander Kaminskii

Proc. SPIE. 4914, High-Power Lasers and Applications II

KEYWORDS: Ceramics, Crystals, Laser crystals, Semiconductor lasers, Absorption, Nd:YAG lasers, Neodymium, Ytterbium, Laser damage threshold, Glasses

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Proceedings Article | 10 June 2002 Paper

Acousto-optical tomography by coaxial detection with frequency-swept ultrasound modulation

Yong Yao, Da Xing, Ken-ichi Ueda

Proc. SPIE. 4618, Biomedical Optoacoustics III

KEYWORDS: Tomography, Ultrasonography, Transducers, Modulation, Ultrasonics, Tissue optics, Image resolution, Photons, Avalanche photodetectors, Laser optics

Proceedings Article | 6 June 2002 Paper

Tumor detection with sonodynamic chemiluminescence from ATX-70 and FCLA under ultrasonic excitation

Yonghong He, Da Xing, Yong Yao, Guihong Yan, Ken-ichi Ueda

Proc. SPIE. 4612, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XI

KEYWORDS: Tumors, Chemiluminescence, Oxygen, Ultrasonography, Tissues, Ultrasonics, In vitro testing, Sonoluminescence, In vivo imaging, Diagnostics

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Proceedings Article | 29 October 2001 Paper

Side pumping of double clad fiber laser with a nonfusional fiber coupler

Jianqiu Xu, Junhua Lu, Jianren Lu, Ken-ichi Ueda

Proc. SPIE. 4594, Design, Fabrication, and Characterization of Photonic Devices II

KEYWORDS: Fiber couplers, Fiber lasers, Polishing, Optical pumping, Adhesives, Cladding, Interfaces, Fiber to the x, Neodymium, Helium neon lasers

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Proceedings Article | 29 October 2001 Paper

High-power diode-pumped passively Q-switched Nd:S-VAP laser with Cr4+:YAG crystal saturable absorber

Deyuan Shen, Ding Tang, Siu Chung Tam, Ken-ichi Ueda

Proc. SPIE. 4595, Photonic Systems and Applications

KEYWORDS: YAG lasers, Chromium, Laser crystals, Q switched lasers, Absorption, Semiconductor lasers, Crystals, Nd:YAG lasers, Laser development, High power lasers

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Proceedings Article | 25 October 2001 Paper

Chemiluminescence detection from sonodynamic action in vitro and in vivo

Yonghong He, Da Xing, Guihong Yan, Ken-ichi Ueda

Proc. SPIE. 4597, Biophotonics Instrumentation and Analysis

KEYWORDS: Oxygen, Tumors, Chemiluminescence, In vivo imaging, In vitro testing, Ultrasonography, Tissues, Stereolithography, Amplifiers, Photons

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Proceedings Article | 25 October 2001 Paper

Coaxial acousto-optical tomography

Yong Yao, Da Xing, Ken-ichi Ueda

Proc. SPIE. 4597, Biophotonics Instrumentation and Analysis

KEYWORDS: Tomography, Ultrasonography, Transducers, Ultrasonics, Tissue optics, Image resolution, Modulation, Photons, Tissues, Fiber lasers

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Proceedings Article | 1 May 2001 Paper

Highly efficient ultra-broadband supercontinuum generation centered at 1484 nm using Raman fiber laser

Mahendra Prabhu, Nam Seong Kim, Jianren Lu, Jianqiu Xu, Ken-ichi Ueda

Proc. SPIE. 4268, Growth, Fabrication, Devices, and Applications of Laser and Nonlinear Materials

KEYWORDS: Raman spectroscopy, Fiber Bragg gratings, Fiber lasers, Single mode fibers, Continuous wave operation, Mirrors, Reflectivity, Supercontinuum generation, Optical fibers, Fiber optics

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Proceedings Article | 24 April 2001 Paper

Efficient diode-pumped double-clad Tm-doped silica fiber laser with a ring cavity

Jianqiu Xu, Jianren Lu, Mahendra Prabhu, Ken-ichi Ueda

Proc. SPIE. 4270, Laser Resonators IV

KEYWORDS: Fiber lasers, Reflectivity, Output couplers, Semiconductor lasers, Absorption, Objectives, Optical fibers, Mirrors, Fabry–Perot interferometers, Thulium

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Proceedings Article | 16 April 2001 Paper

Highly efficient polycrystalline Nd:YAG ceramics laser

Jianren Lu, T. Murai, K. Takaichi, T. Uematsu, K. Misawa, Ken-ichi Ueda, Hideki Yagi, T. Yanagitani, Alexander Kaminskii

Proc. SPIE. 4267, Solid State Lasers X

KEYWORDS: Ceramics, Nd:YAG lasers, Laser crystals, Crystals, Neodymium, Mirrors, Optical pumping, High power lasers, Virtual point source, Continuous wave operation

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Proceedings Article | 25 January 2001 Paper

Energy extraction performance for a diode-pumped CPA system in Yb-doped materials at low temperature

Junji Kawanaka, Hajime Nishioka, Norihiro Inoue, Yoshinori Kubota, Ken-ichi Ueda

Proc. SPIE. 4184, XIII International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference

KEYWORDS: Absorption, Semiconductor lasers, Energy efficiency, Crystals, Polarization, Pulsed laser operation, Oscillators, Glasses, Laser damage threshold, Laser development

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Proceedings Article | 25 January 2001 Paper

High-power cw Raman fiber laser using phosphosilicate fiber pumped by Yb-doped double-clad fiber laser

Mahendra Prabhu, Nam Seong Kim, Jianren Lu, Ken-ichi Ueda

Proc. SPIE. 4184, XIII International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference

KEYWORDS: Fiber lasers, Fiber Bragg gratings, Raman spectroscopy, Reflectivity, Mirrors, Output couplers, Silicon, Continuous wave operation, Raman scattering, Fiber amplifiers

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Proceedings Article | 25 January 2001 Paper

Highly efficient lasers using polycrystalline Nd:YAG ceramics

Jianren Lu, Mahendra Prabhu, Ken-ichi Ueda, Hideki Yagi, T. Yanagitani, Alexis Kudryashov

Proc. SPIE. 4184, XIII International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference

KEYWORDS: Ceramics, Nd:YAG lasers, Crystals, Laser crystals, Virtual point source, High power lasers, Mirrors, Optical pumping, Absorption, Laser damage threshold

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Proceedings Article | 11 October 2000 Paper

Enhanced sonoluminescence of tissues

Yonghong He, Da Xing, Yong Yao, Yonghong Tang, Shici Tan, Ken-ichi Ueda

Proc. SPIE. 4224, Biomedical Photonics and Optoelectronic Imaging

KEYWORDS: Tissues, Stereolithography, Liver, Sonoluminescence, Ultrasonography, Cavitation, Signal detection, Oxygen, Molecules, Chemiluminescence

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Proceedings Article | 11 October 2000 Paper

New method of ultrasound-modulated optical tomography

Yong Yao, Da Xing, Yonghong He, Ken-ichi Ueda

Proc. SPIE. 4224, Biomedical Photonics and Optoelectronic Imaging

KEYWORDS: Modulation, Ultrasonography, Tissue optics, Ultrasonics, Signal to noise ratio, Tomography, Biomedical optics, Ultrasound-modulated optical tomography, Amplitude modulation, Light scattering

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Proceedings Article | 9 October 2000 Paper

Mutual effects of stimulated Raman scattering and four-wave mixing in phosphosilicate fibers

Jianqiu Xu, Cheng Li, Jianren Lu, Ken-ichi Ueda

Proc. SPIE. 4225, Optical Interconnects for Telecommunication and Data Communications

KEYWORDS: Raman spectroscopy, Optical fibers, Raman scattering, Four wave mixing, Modulation, Silica, Laser scattering, Fiber lasers, Nd:YAG lasers, Polarization

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Proceedings Article | 3 April 2000 Paper

Frequency-stabilized injection-locked laser

Mitsuru Musha, Takeshi Kanaya, Ken-ichi Ueda