Hidetaka Nishi
Tokyo Institute of Technology
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Hidetaka Nishi.
Proceedings of SPIE, the International Society for Optical Engineering | 2010
Koji Yamada; Hiroshi Fukuda; Tai Tsuchizawa; Toshifumi Watanabe; Hiroyuki Shinojima; Hidetaka Nishi; Songbong Park; Yasuhiko Ishikawa; Kazumi Wada; Seiichi Itabashi
Silicon photonic wire waveguides, featuring very strong optical confinement and compatibility with silicon electronics, provide a compact photonic platform on which passive, dynamic, and active photonic devices can be integrated. We have already developed a low-loss waveguide platform and integrated various photonic devices. For passive devices, we have developed polarization-independent wavelength filters using a monolithically integrated polarization diversity circuit, in which waveguide-based polarization manipulation devices are implemented. The polarization-dependent loss of a ring resonator wavelength filter with polarization diversity is less than 1 dB. For dynamic devices, we have developed compact carrier-injection-type variable optical attenuators (VOAs). The length of the device is less than one millimeter, and the response time is nanosecond order. The device has already been made polarization independent. We have recently monolithically integrated these fast VOAs with low-dark-current germanium photodiodes and achieved synchronized operation of these devices. For nonlinear devices, a free-carrier extraction structure using a PIN junction implemented in the waveguide can increase the efficiency of nonlinear functions. For example, in a wavelength conversion based on the Four-wave-mixing effect, the conversion efficiency can be increased by 6 dB.
Photonics in Switching | 2017
Nikolaos Panteleimon Diamantopoulos; Wataru Kobayashi; Hidetaka Nishi; Koji Takeda; Takaaki Kakitsuka; Shinji Matsuo
For low-cost reach extension of 400G Ethernet, >50-Gb/s PAM-4 at 1.3-μm over 40-km is demonstrated without optical amplification, enabled by a high-speed and high launch power directly modulated laser, PIN-photodiode, and low-complexity equalization.
Proceedings of SPIE, the International Society for Optical Engineering | 2009
Koji Yamada; Hiroshi Fukuda; Tai Tsuchizawa; Toshifumi Watanabe; Hiroyuki Shinojima; Hidetaka Nishi; Seiichi Itabashi
We devised a silicon photonic circuit with polarization diversity. The circuit consists of polarization splitters and rotators. The splitter is based on simple 10-micrometer-long directional couplers. The polarization extinction ratio is 23 dB and excess loss is less than 0.5 dB. The rotator consists of a silicon waveguide embedded in an off-axis siliconoxynitride waveguide. A 35-micrometer-long rotator gives a rotation angle of more than 72 degrees and excess loss of about 1 dB. Both devices can be made by using planar fabrication technology and do not require a complex structure such as three-dimensional forming. Using these devices, we developed a polarization diversity circuit for a ringresonator wavelength filter. The polarization dependent loss of the filter with polarization diversity is about 1 dB. A 10- Gbps data transmission with scrambled polarization is demonstrated.
Journal of Solid Mechanics and Materials Engineering | 2009
Yuuki Ohsone; Hidetaka Nishi; Masanori Saito; Masaki Suzuki; Hiroya Murakami; Naoto Ohtake
OECC 2010 Technical Digest | 2010
Sungbong Park; Koji Yamada; Tai Tsuchizawa; Toshifumi Watanabe; Hidetaka Nishi; Hiroyuki Shinojima; Seiichi Itabashi
Archive | 2009
Seiichi Itabashi; Hidetaka Nishi; Hiroyuki Shinojima; Yasushi Tsuchizawa; Toshibumi Watanabe; Koji Yamada; 泰 土澤; 浩治 山田; 聖一 板橋; 俊文 渡辺; 弘幸 篠島; 英隆 西
Archive | 2007
Tsutomu Matsui; Jun Mochizuki; Hiroya Murakami; Hidetaka Nishi; Naoto Otake; Takuya Samejima; 尚登 大竹; 純 望月; 碩哉 村上; 務 松井; 英隆 西; 拓也 鮫島
ECS Transactions | 2018
Tatsurou Hiraki; Takuma Aihara; Koichi Hasebe; Takuro Fujii; Koji Takeda; Hidetaka Nishi; Takaaki Kakitsuka; Hiroshi Fukuda; Tai Tsuchizawa; Shinji Matsuo
PRiME 2016/230th ECS Meeting (October 2-7, 2016) | 2016
Hidetaka Nishi; Tai Tsuchizawa; Takaaki Kakitsuka; Koichi Hasebe; Koji Takeda; Tatsuro Hiraki; Takuro Fujii; Tsuyoshi Yamamoto; Shinji Matsuo
Proceedings of the IEICE General Conference | 2015
Akihiro Noriki; Takeru Amano; Daisuke Shimura; Yosuke Onawa; Hironori Sasaki; Koji Yamada; Hidetaka Nishi; Tai Tsuchizawa; Shigeya Ukita; Mikiko Sasaki; Masahiko Mori