What is the THz region?
- Is it a spectrum with some special features ,or is it a spectrum
happened to lie between the millimeter, microwave range on one side and
the infrared, optical range on the other ?-
Prof. Koji Mizuno
- Presentation Abstract
The terahertz (THz) wave range of the electromagnetic spectrum extends from 0.1 to 10 THz with 1 THz occurring in the middle of the range. In 1970 a Symposium on Submillimeter Waves was held in New York, and this would be the first International Conference covering the THz region. In that period the motives to develop THz technologies were studies on nuclear-fusion-plasma and also traditional far-infrared (mainly gas) spectroscopy. In 1980's a lot of studies to diagnose and to heat up high-density plasma were developed. After 1990 TDS (Time Domain spectroscopy) technologies using short-pulse lasers have been introduced in the THz region, which extended significantly far-infrared spectroscopy technologies. These movement have brough a kind of THz boom at that time and the boom was continued until the early of 2000's. At that time even large economic impact with THz technologies was predicted, however still now being far from the prediction.
The boom of THz technologies movement, in my opinion, was temporary and has now been passed. The main direction of the THz technology development has returned to communication areas to realize high-density, high-speed information exchange, as expected since before in a way. The millimeter wave region, an immediate neighbor spectrum of the THz, is at present showing an real example for the same direction using CMOS technologies, compound semiconductor devices, hybrid electronic-photonic systems, etc.
Here it would be worth showing that the THz region has some interesting features that the millimeter and the infrared regions have not. The THz region is not only the spectrum boundary but also the transition region where various physical phenomina change. For instance, the high frequency limitations of operation of various microwave-type electron devices are in the THz. The limitations of transistors and klystrons (microwave-type electron tubes) exist in the terahertz range.
Another example is on the thermal radiation. It is well known that all materials around us emit the thermal radiation, and the major part of this radiation intensity from room-temperature materials is, interestingly, the THz region. The thermal radiation is caused by the scattered movement of electrons in materials, which is very fundamental phenomenum in solids from the ancient period of the earth. These phonomena give the impression that the THz region would be special, unique spectrum.
In this talk, I would like to talk about some unique phonomena in the THz region, for the understanding of these phonomena would be useful to develop THz devices for future ICT, information and communications technology.
Koji Mizuno received the B.Eng., M.Eng., and D.Eng. degrees in electronic engineering from Tohoku University, Sendai, Japan, in 1963, 1965, and 1968, respectively.
In 1968, he joined the Department of Electronic Enginnering, Tohoku University as a Research Associate. He was apponited Associate Professor at the Research Institute of Electrical Communication (RIEC), Tohoku University in 1972, and Professor of Electron Devices there in 1984. In March 2004 he retired from his appointment to become an Emeritus Professor. He spent a sabbatical at Queen Mary College, Univerity of London under the sponsorship of the SRC (Science Research Council, United Kingdom) in 1972 - 1973, and in 1990 he spent a six-month sabbatical at the California Institute of Technology, Pasadena and Queen Mary and Westfield College, London under the sponsorship of Monbusho (Ministry of Education, Science and culture, Japan). From 1990 to 1998 he was a team leader of the Photodynamics Research Center, the Institute of Physical and Chemical Research (RIKEN), Sendai, where he ran a laboratory for submillimeter wave research at the same time as he ran the laboratory at Tohoku University. He has been interested in the millimeter and submillimeter-wave (THz) region of the electromagnetic wave spectrum, and he has been continuously developing technologies of detection, generation and applications in this frequency regime.
He was awarded the IEEE Fellow grade in 1993, the Kenneth J. Button Medal in 1998, the Minister Award of MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan) in 2003, the Distinguished Educator Award of the IEEE Microwave Theory and Techniques Society in 2005, and the Exceptional Service Award of the International Society of Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) in 2015. His hobbies are sailing and playing the flute.