Yasushi Koyama
Canon Inc.
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Featured researches published by Yasushi Koyama.
Applied Physics Express | 2013
Yasushi Koyama; Ryota Sekiguchi; Toshihiko Ouchi
Oscillations from 1.02 to 1.40 THz were observed at room temperature from resonant-tunneling-diode (RTD)-based oscillators with integrated patch antennas by improving the mesa structure and tuning the length of the antenna and the feed point location of the RTD. A two-step post structure realized a reduction of series resistance of the RTD, and the oscillation frequency significantly increased with the feed point closer to the center of patch antenna at around 1 THz. Experimental results agreed well with the analysis.
Applied Physics Letters | 2010
Ryota Sekiguchi; Yasushi Koyama; Toshihiko Ouchi
We report on subterahertz oscillations of resonant tunneling diode oscillators with an integrated patch antenna. The device consists of an InGaAs/InAlAs triple-barrier resonant tunneling diode and a patch antenna on an InP substrate. Current-voltage characteristics indicate a peak current density of 280u2002kA/cm2, with a peak-valley ratio of about 3 at room temperature. An oscillation frequency of 517 GHz was observed at room temperature through Fourier transformed infrared spectroscopy. The results agree with electromagnetic analysis.
Journal of Infrared, Millimeter, and Terahertz Waves | 2014
Toshihiko Ouchi; Kousuke Kajiki; Takayuki Koizumi; Takeaki Itsuji; Yasushi Koyama; Ryota Sekiguchi; Oichi Kubota; Kodo Kawase
Archive | 2004
Haruhito Ono; Masatake Akaike; Kenji Tamamori; Futoshi Hirose; Yasushi Koyama; Atsunori Terasaki; Kenichi Nagae; Yoshinori Nakayama
Archive | 2009
Yasushi Koyama; Takeaki Itsuji; Toshihiko Ouchi
Archive | 2012
Yasushi Koyama
Archive | 2011
Yasushi Koyama; Kousuke Kajiki
Archive | 2008
Yasushi Koyama; Ryota Sekiguchi
Archive | 2007
Yasushi Koyama; Hiroyuki Ogino; 泰史 小山; 宏幸 荻野
Archive | 2010
Yasushi Koyama; Ryota Sekiguchi