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Dive into the research topics where Yasuhiro Uchiyama is active.

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Featured researches published by Yasuhiro Uchiyama.


Japanese Journal of Applied Physics | 2005

1.2 µm Band GaInAs/GaAs High-Density Multiple-Wavelength Vertical Cavity Surface Emitting Laser Array

Yasuhiro Uchiyama; Takashi Kondo; Kazutaka Takeda; Akihiro Matsutani; Takeshi Uchida; Tomoyuki Miyamoto; Fumio Koyama

We demonstrate a densely packed multi-wavelength GaInAs/GaAs vertical cavity surface emitting laser array emitting in 1200 nm wavelength band. 110-channel emitters could be integrated in a 2.2 mm long bar with spatial spacing of 20 µm and wavelength spacing of 0.1 nm. All the emitters exhibit single mode operation with output power of over 1 mW. The wavelength separation is precisely controlled by adjusting the bias current of each element.


Japanese Journal of Applied Physics | 2006

Wavelength Extension Effect on Lasing Characteristics of Highly-Strained GaInAs/GaAs Vertical-Cavity Surface-Emitting Lasers with Cavity Detuning

Kazutaka Takeda; Tomoyuki Miyamoto; Takashi Kondo; Yasuhiro Uchiyama; Naoto Kitabayashi; Takeshi Uchida; Akihiro Matsutani; Fumio Koyama

Cavity detuned highly-strained GaInAs/GaAs vertical cavity surface emitting lasers (VCSELs) were investigated. Devices emitting beyond 1.2 µm of the wavelength were realized by combining conventional quantum wells emitting at 1.18 µm and large wavelength detuned cavities. Various detuning conditions from -35 to 80 nm were compared for clarifying the detuning effect. The longest wavelength was 1.27 µm for an 80 nm detuned device. The highest operating temperature of a 55 nm detuned device was 140 °C under cw operation. It was found that approximately 50 nm detuning was necessary to reach the threshold gain level for a large detuned device and the condition was produced by self-heating. Relaxation resonance frequencies were characterized and over 2 GHz was observed even for a 1.27 µm VCSEL.


lasers and electro optics society meeting | 2005

Electro-thermal wavelength tuning of 1.2 /spl mu/m GaInAs/GaAs vertical cavity surface emitting laser array

Yasuhiro Uchiyama; Takashi Kondo; Kazutaka Takeda; Akihiro Matsutani; Takeshi Uchida; Tomoyuki Miyamoto; Fumio Koyama

This paper demonstrates an electro-thermally tunable VCSEL array with an additional tuning electrode. The VCSEL array achieves continuous wavelength tuning of approximately 3 nm with a single-tuning-contact. The deviation in output power is within 1 dB. The power consumption for wavelength tuning is as low as 46 mW. Fast tuning response is expected in the proposed tunable VCSEL because of the small thermal capacity.


lasers and electro-optics society meeting | 2004

Highly strained GaInAs/GaAs 1.21 /spl mu/m vertical cavity surface emitting laser with single-mode output power of 3 mW

Takashi Kondo; Yasuhiro Uchiyama; Kazutaka Takeda; Akihiro Matsutani; Tomoyuki Miyamoto; Fumio Koyama

A highly strained GaInAs/GaAs VCSEL emitting at 1.21 /spl mu/m is demonstrated. The threshold current is 1.3 mA. The maximum single mode output power of 3 mW is achieved. These results indicate that a highly strained 1.2 /spl mu/m range GaInAs VCSEL can be useful for high capacity metro-area networks.


lasers and electro-optics society meeting | 2004

1.2 /spl mu/m band high-density multiple-wavelength vertical cavity surface emitting laser array

Yasuhiro Uchiyama; Takashi Kondo; Kazutaka Takeda; Akihiro Matsutani; J. Hashizume; U. Tajeshi; Tomoyuki Miyamoto; Fumio Koyama

A 1.2 /spl mu/m band densely packed VCSEL array with highly strained GaInAs/GaAs QWs with spatial spacing of 20 /spl mu/m and wavelength spacing of 0.1 nm is demonstrated for the first time. A large number of VCSELs of over 100 elements could be integrated in a 2 mm long bar.


Archive | 2004

METHOD OF TREATING EXHAUST GAS FROM CEMENT KILN

Takashi Kondo; Junichi Terasaki; Yasuhiro Uchiyama; Osamu Yamaguchi; 康広 内山; 淳一 寺崎; 修 山口; 尚 近藤


Archive | 2008

Fired product, cement additive, and cement composition

Kenichi Honma; Makoto Kobayakawa; Daisuke Kurokawa; Yasuhiro Uchiyama; 康広 内山; 真 小早川; 健一 本間; 大亮 黒川


Archive | 2008

Method for treating exhaust gas from cement manufacturing equipment

Akitoshi Kidachi; Yasushi Kondou; Masafumi Nakasaki; Junichi Terasaki; Yasuhiro Uchiyama; Osamu Yamaguchi; 雅文 中崎; 康広 内山; 淳一 寺崎; 修 山口; 明利 木立; 耕史 近藤


Archive | 2005

Apparatus and method for manufacturing cement

Takashi Kondo; Shunkichi Sudo; Junichi Terasaki; Yasuhiro Uchiyama; Osamu Yamaguchi; 康広 内山; 淳一 寺崎; 修 山口; 尚 近藤; 俊吉 須藤


IEICE Electronics Express | 2004

Thermal cross-talk evaluation of densely integrated vertical cavity surface emitting laser array

Yasuhiro Uchiyama; Takashi Kondo; Kazutaka Takeda; Akihiro Matsutani; Takeshi Uchida; Tomoyuki Miyamoto; Fumio Koyama

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Takashi Kondo

Tokyo Institute of Technology

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Akihiro Matsutani

Tokyo Institute of Technology

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Fumio Koyama

Tokyo Institute of Technology

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Kazutaka Takeda

Tokyo Institute of Technology

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Tomoyuki Miyamoto

Tokyo Institute of Technology

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