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Dive into the research topics where Ryota Sekiguchi is active.

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Featured researches published by Ryota Sekiguchi.


Applied Physics Express | 2013

Oscillations up to 1.40 THz from Resonant-Tunneling-Diode-Based Oscillators with Integrated Patch Antennas

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

Subterahertz oscillations from triple-barrier resonant tunneling diodes with integrated patch antennas

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 280 kA/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

Terahertz Imaging System for Medical Applications and Related High Efficiency Terahertz Devices

Toshihiko Ouchi; Kousuke Kajiki; Takayuki Koizumi; Takeaki Itsuji; Yasushi Koyama; Ryota Sekiguchi; Oichi Kubota; Kodo Kawase


Archive | 2007

Detection device and image forming device

Ryota Sekiguchi; Toshihiko Ouchi


Archive | 2006

Device for generating or detecting electromagnetic radiation, and fabrication method of the same

Toshihiko Ouchi; Ryota Sekiguchi


Archive | 2005

Quantum cascade laser device

Ryota Sekiguchi; Toshihiko Ouchi


Archive | 2006

Frequency Tunable Oscillator

Ryota Sekiguchi; Toshihiko Ouchi


Archive | 2008

RESONANT TUNNELING STRUCTURE

Yasushi Koyama; Ryota Sekiguchi


Archive | 2007

Photonic-crystal electromagnetic-wave device including electromagnetic-wave absorptive portion and method for producing the same

Shinan Wang; Ryota Sekiguchi


Archive | 2011

ELECTROMAGENTIC-WAVE GENERATION DEVICE

Ryota Sekiguchi

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Masahiro Okuda

Osaka Prefecture University

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