Prof Safumi Suzuki, Tokyo Institute of Technology, Japan, will be visiting the School of Engineering. As part of his visit he will deliver a seminar entitled, "Resonant-Tunnelling-Diode Terahertz Oscillators and its Applications". Abstract and biography are given below.

Date & Time: 14:00, Thursday, 6th October
Venue: Room 514, Rankine Building

Abstract

Compact and coherent source is a key component for various applications of the terahertz wave. We report on our recent results of terahertz oscillators using resonant tunnelling diodes (RTDs). The RTD is an InGaAs/AlAs double-barrier structure on InP substrate, and integrated with a planar slot antenna as a resonator and radiator. The output power is obtained from the substrate side through a Si lens. To achieve high-frequency oscillation, a narrow quantum well and an optimized collector spacer thickness were used. The former reduces the electron dwell time in the resonant tunneling region and the latter simultaneously reduces the electron transit time and the capacitance at the collector depletion region. The conduction loss of the slot antenna was also reduced with an optimized antenna length and an improved air bridge structure between the RTD and antenna. By these structures, fundamental oscillation up to 1.92 THz were obtained at room temperature. Oscillation above 2 THz is further expected in theoretical calculation. An oscillator with dipole antenna array, in which a Si lens is unnecessary, was fabricated. In a preliminary experiment, output power of 440 μW was obtained at 0.9 THz in a three-element array. Wireless data transmission using direct intensity modulation was demonstrated with the data rate of 34 Gbps and the bit error rate below the forward error correction limit. By integrating a varactor into the slot antenna, electrical frequency tuning was achieved with a tuning range of 580-900 GHz in an array device. Application of frequency-tunable RTD oscillators to measurements of absorption spectra was also demonstrated.

Biography

Safumi Suzuki received the B.E. degree in Electrical and Electronic Engineering and the M.E. and D.E. degrees in Electronics and Applied Physics from the Tokyo Institute of Technology, Japan, in 2005, 2007, and 2009, respectively. From 2009 to 2014, he was an Assistant Professor in the Department of Electronics and Applied Physics, Tokyo Institute of Technology, and was an Associate Professor in the Department of Physical Electronics from 2014 to 2016. He has been an Associate Professor in the Department of Electrical and Electronic Engineering since 2016. He is currently engaged in research on THz electron devices.

First published: 23 September 2016

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