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Start Over Author "Shinji Motokoshi" Journal the review of laser engineering
20 results on '"Shinji Motokoshi"'

9. Study of Solar Pumped Laser for Fossil-fuel-free Energy Cycle Using Magnesium

Author

Shinji Motokoshi, Kouichirou Kido, Takayuki Funatsu, Norihito Yasunaga, Tomomasa Ohkubo, Yuji Sato, Takehiro Oishi, Kunio Yoshida, Minoru Yoshida, Sigeaki Uchida, Manabu Ishioka, Takagimi Yanagidani, Kiyoshi Kato, Yuichirou Nakayama, Behgol Bagheri, Choijil Baasandash, Takashi Yabe, Yoshiaki Okamoto, Masahiro Nakatsuka, and Kazuya Daito

Subjects
Materials science, business.industry, Magnesium, Fossil fuel, chemistry.chemical_element, Fresnel lens, Solar-pumped laser, Concentrator, Laser, law.invention, Energy cycle, Optics, chemistry, law, visual_art, visual_art.visual_art_medium, Ceramic, business
Abstract

A new type of solar pumped laser system that has features of high-efficiency and low cost due to the use of a Fresnel lens and a Cr codoped Nd:YAG ceramic laser medium is reported in this paper. Slope efficiencies of 7 to 9% have been achieved. The laser output of about 80 W was achieved with the combination of a 4-m2 Fresnel lens and solar light chamber as a secondary power concentrator. The maximum output from a unit area of the Fresnel lens was 20 W/m2, which is 2.8 times larger than the previous results with a mirror type concentrator.

Published
2008
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11. Solid-State Clad Lasers under Quasi-Solar-Pumping

Author

Shinji Motokoshi, Yasukazu Izawa, Masahiro Nakatsuka, Hisanori Fujita, Taku Saiki, Chiyoe Yamanaka, Kazuo Imasaki, and Shigeaki Uchida

Subjects
Materials science, business.industry, law, Solid-state, Optoelectronics, business, Laser, law.invention
Published
2006
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12. A Nd doped Multimode-Fiber-Laser with D-Shape Large Clad under Quasi-Solar-Pumping

Author

Minoru Yoshida, Taku Saiki, Masahiro Nakatsuka, Shinji Motokoshi, Chiyoe Yamanaka, Kazuo Imasaki, Hideaki Ito, Yasukazu Izawa, Hisanori Fujita, and Shigeaki Uchida

Subjects
Multi-mode optical fiber, Materials science, business.industry, Doping, chemistry.chemical_element, Laser, Neodymium, law.invention, chemistry, law, Fiber laser, Optoelectronics, D-Shape, business
Published
2004
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13. Development of High Repetition LD-Pumped Solid-State Laser

Author

Hidetsugu Yoshida, Koji Tsubakimoto, Shinji Motokoshi, Hisanori Fujita, Masahiro Nakatsuka, and Yasushi Fujimoto

Subjects
Materials science, business.industry, Amplifier, Laser, law.invention, Optics, Fiber Bragg grating, Solid-state laser, law, Brillouin scattering, Fiber laser, Laser power scaling, business, Faraday rotator
Abstract

In the Leading Project of MEXT from 2003, Japan, high average power LD-pumped YAG lasers are being developed with specifications of > 1 J, > 5 kHz, and 1-10-ns pulse. All fiber front end system consists of cw 40-mW Yb doped fiber laser (YbDFL) with a fiber Bragg grating cavity, a pulse shaper of LiNbO3, and three stages of YbDFL amplifiers, delivering 2-mW average power of 1-20 ns pulses in 5-kHz repetition rate. The design and test of 500-W class LD-pumped booster amplifier head is discussed. Some key elements of technology for high-peak and high-average power system are reviewed such as a ten-cm silica laser material, a repetitive work of stimulated Brillouin scattering phase conjugate mirror for 10-kW capability, a ceramic material for Faraday rotator for high-average power level, so on.

Published
2004
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14. Calculation of Excitation and Oscillation for a Solid-State Laser under Coaxial Pumping with Solar Light by Using a Collector Structure with Asymmetrical Profile

Author

Kouji Tsubakimoto, Chiyoe Yamanaka, Kazuo Imasaki, Yasukazu Izawa, Hisanori Fujita, Shigeaki Uchida, Taku Saiki, Masahiro Mori, Shinji Motokoshi, Hiroyuki Nagayama, and Masahiro Nakatsuka

Subjects
Optics, Materials science, Solid-state laser, business.industry, Oscillation, Solar light, Laser pumping, Coaxial, business, Excitation
Published
2002
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15. Repairing of Cr-photo-mask by ultrafast- pulse laser

Author

Hiroko Okuyama, Motoki Watanabe, Mamoru Okutomi, Masanao Tani, Takeyo Tsukamoto, Takeyoshi Nakayama, Yuki Kondo, Masaru Sugirua, S. Oyama, Y. Kawasaki, Satoshi Ihara, N. Morirnoto, A. Yokotani, M. Tomita, Quan Li, S. Kubodera, H. Takakusaki, Yoshihisa Uchida, Toshio Goto, Tatuya Kyotani, Jianrong Qiu, H. Yanagita, Keiu Tokumura, Masataka Murahara, Katsunori Tsunoda, Jun Yamada, Hirotaka Nakayama, Nobuyuki Takahashi, Akira Obara, Noriaki Nishi, Nobuo Ando, Nobuo Isii, T. Hashidume, S. Yosihara, Zhengxin Liu, K. Sugioka, Takashi Inoue, K. Miura, Shigeru Yamaguchi, Tetsuya Hattori, H. Matsuno, T. Ikagame, Kouji Higashikawa, Xiaoyang Zeng, Takeshi Sasaki, Jun Kamiiisaka, H. Sano, Hideo Furuhashi, Y. Kawakami, Mineo Hiramatu, Tetukazu Tanaka, Hirofumi Yajima, T. Kawashima, A. Masagaki, Takashi Obara, Sadao Fujii, T. Mori, Takuya Takasaki, Y. Mase, Kozo Yasuda, Yoshiyuki Uchida, M. Ishii, Takenari Mori, Y. Shinto, K. Kadota, Kunimitsu Takahashi, Hiromi Kawase, Takahisa Jitsuno, Masayuki Okoshi, J. Kawanaka, Naoto Koshizaki, Hitoki Yoneda, N.B. Dahotre, H. Ashizawa, Kenichi Ueda, Shigeto Kobayashi, Tomoo Fujioka, Akinori Kaji, T. Hirayama, Nobuo Yasunaga, K. Makino, Masafumi Ito, Akihiro Kono, R. Nomura, Hikaru Kouta, Hideyuki Horisawa, Chobei Yamabe, Kazuyuki Akagawa, Shinji Motokoshi, Tadahiro Ishii, Kazuyuki Hirao, Naoshige Hayashi, J. Nakata, N. Takezoe, S. Ito, Hiroyuki Niino, Mitsugu Hanabusa, J. Morimoto, Keiji Fuse, Yukinori Hato, Sachiko Umeda, Satoru Nishio, Koichi Toyoda, Naokatsu Yamamoto, Y. Minami, T. Kubota, Yukio Nakajima, Hiroyasu Sato, Masaru Hori, H. Takai, Nobuhiro Akasaka, Hiroshi Ito, E. Ozawa, Takeshi Okada, Kazuyoshi Tanaka, W. Sasaki, Mikio Muro, K. Midorikawa, Tsuguru Shirakawa, M. Hasegawa, T. Suzuki, Saburoh Satoii, Masahiro Nakatsuka, Masayuki Nakamura, T. Igarashi, Shigenori Kuriki, Keiji Ebata, Tadatake Sato, Shinnosuke Nozaki, Manabu Shiozaki, K. Suzuki, Kazushi Fujita, K. Hirobe, T. Mitsuyu, H. Iizuka, Hironari Mikata, Koichi Tsukamoto, K. Obata, K. Kurosawa, K. Kumagai, Masashi Ishimine, Takashi Fushimi, Shigeru Semura, T. Sato, Akira Yabe, Koichi Sasaki, Kazuyuki Okada, S. Nakjima, Y. Maezono, and Akiyoshi Matsuzaki

Subjects
Femtosecond pulse shaping, X-ray laser, Materials science, business.industry, Optoelectronics, Photomask, business, Ultrashort pulse, Pulsed laser deposition
Published
1999
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16. The Field Experiments of Laser Triggered Lightning

Author

Chiyoe Yamanaka, Tomoo Ushio, Zen Kawasaki, Yuuji Ishikubo, Teiji Watanabe, Mikio Adachi, Shinji Motokoshi, Hirohiko Yasuda, Tatsuhiko Yamanaka, K. Matsuura, Daohong Wang, Kouji Tsubakimoto, Shigeaki Uchida, Hisanori Fujita, and Yoshinori Shimada

Subjects
Meteorology, Field (physics), law, Environmental science, Thundersnow, Laser, Lightning, Field observation, Remote sensing, law.invention
Abstract

A field experimental site for laser triggered lightning (LTL) has been prepared targetting the winter thunderstorms in Hokuriku region. This paper discusses the results from laboratory experiments and field observation on winter thunderstorms at Mihama district. A new scheme of determining the laser irradiation timing, the PB (Preliminary Breakdown) trigger, and its preliminary results on LTL are also described.

Published
1996
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17. Study on Laser Triggered Discharge Using a CO2 Laser

Author

Zen Kawasaki, Yasuyuki Watada, Chiyoe Yamanaka, Daohong Wang, Tatsuhiko Yamanaka, Shigeaki Uchida, Shinji Motokoshi, Yoshinori Shimada, Yuuji Ishikubo, Mikio Adachi, and Hirohiko Yasuda

Subjects
Materials science, business.industry, Physics::Optics, Laser pumping, Plasma, Laser, Lightning, law.invention, Optics, Physics::Plasma Physics, law, Excited state, Ionization, Physics::Space Physics, Cathode ray, Plasma channel, Physics::Atomic Physics, business, Physics::Atmospheric and Oceanic Physics
Abstract

We are preparing a laser triggered lightning method for the winter thunderstorm. Using a - 150-J electron beam excited CO2 laser, we obtained a laser plasma channel consisting of many plasma beads made of ionized aerosols in the atmosphere. The laser plasma channel initiates an electrical streamer and propagates a leader. We discuss experimental results on the critical conditions for initiating streamer from a laser plasma channel and for leader propagation through a laser plasma channel.

Published
1996
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18. Fundamental Experiments on Laser Triggered Lightning. Plasma Generation under Winter Thunderstorms

Author

Shinji Motokoshi, Chiyoe Yamanaka, Yoshinori Shimada, Yuuji Ishikubo, Mikio Adachi, Yasukazu Izawa, Kouji Tsubakimoto, Hirohiko Yasuda, Zen Kawasaki, Hisanori Fujita, Shigeaki Uchida, and Tatsuhiko Yamanaka

Subjects
Atmosphere, law, Attenuation, Environmental science, Plasma channel, Plasma, Laser, Snow, Lightning, Corona discharge, Remote sensing, law.invention
Abstract

It is a crucial issue to make an intense plasma channel in the atmosphere for laser triggered lightning. The laser characteristics of laser propagation and plasma generation have been studied under various weather conditions. The line density of plasma channel in snowy weather is less than that in fine weather due to the laser energy attenuation and the decrease of aerosols, the cores of plasma beads, by snow. To initiate a leader at the top of lightning tower, the line density of plasma channel is needed to be over one hundred per meter. Some remedies to overcome this effects will be discussed.

Published
1996
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20. Study on Spectral Characteristics in Near Infrared Semiconductor Laser at a Prism External Cavity System

Author

Nobuhiro Kikuzawa, S. Fukumoto, Takuji Ueno, Takafumi Goto, Eisuke Minehara, K. Ueda, H. Yoneda, Chang hwan Yoon, F. Tsunesada, R. Ono, Y. Mori, Yasuhiko Kuwano, S. Yasuda, Tetsuo Harimoto, Toshihiko Yamauchi, M. Yonemura, Hiroshi Nakao, R. Nagai, Hiroyuki Furuya, K. Kawamura, Kan-ichi Fujii, Shin Ichi Zaitsu, Hirofumi Matsubara, T. Sasaki, Yoke Khin Yap, Tatsuhiko Yamanaka, Shinji Motokoshi, Tomosumi Kamimura, Katuhiro Uno, Masashi Yoshimura, T. Iwai, Takahisa Jitsuno, H. Kouta, T. Kobayashi, Masahiro Nakatsuka, and Yasusi Fujimoto

Subjects
Materials science, Semiconductor, Optics, law, business.industry, Near-infrared spectroscopy, External cavity, Optoelectronics, Prism, Laser, business, law.invention
Published
2001
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