Masayuki Fujita of Osaka University

Terahertz (THz) waves, which represent the frequency region between radio and light waves from 0.1 THz to 10 THz, have attracted considerable attention in the interdisciplinary field of electronics and photonics. Their unique potential applications, such as in ultra-broadband wireless communication, spectroscopic sensing, and non-destructive imaging, are now being developed. However, most existing THz application systems are composed of bulky, discrete and large-power-consumption elements based on photoelectric conversion, hollow waveguides and/or optical components. For the key device in an integrated THz system, we focus on resonant tunneling diodes (RTDs) with semiconductor quantum structures as compact and energy-efficient THz source and detector. The RTD oscillator can generate directly coherent THz waves at room temperature, and an oscillation frequency of approximately 2 THz has been reported. Highly sensitive RTD detectors have been realized by exploiting the strong nonlinear current-voltage characteristics of RTDs. In addition, the integrated platform to manipulate the THz waves in a thin, planar, self-supporting and low-loss structure is indispensable toward the practical use of THz waves in various fields. We focus on a silicon photonic-crystal slab, which enables low-loss confinement of THz waves using periodic dielectric microstructures by photonic bandgap and total internal reflection. An extremely low-loss (< 0.1 dB/cm) THz waveguide, a high-Q (> 10,000) cavity, a compact diplexer, and all-dielectric antenna have been developed. In this seminar, the author will present the recent progress of THz devices and systems based on photonic crystals, RTDs and their integration, which enable compact, low-power consumption, and integrated systems.

Biography:

Masayuki Fujita is an associate professor at the Graduate School of Engineering Science, Osaka University, Japan. He received his Ph.D. degree from Yokohama National University on ultrasmall and ultralow threshold microdisk lasers. Subsequently, he joined the Department of Electronic Science and Engineering at Kyoto University and initiated research on photonic crystals, including spontaneous emission control in photonic crystals and efficient light-emitting diodes and silicon emitters. Next, he moved to Osaka University and was appointed the research director of the strategic basic research program CREST, “Development of terahertz integrated technology platform through fusion of resonant tunneling diodes and photonic crystals” of the Japan Science and Technology Agency. His research interests include terahertz materials, devices and systems, and photonic nano- and micro-structures.

Email:

Address:Graduate School of Engineering Science, Osaka University, Osaka, Japan