1. Division of Electrical, Electronic
and Information Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
2. Research Centre for Development
of Far-Infrared Region, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
3. Graduate School of Science and
Engineering, Yamagata University, 4-3-16
Jonan, Yonezawa-shi, Yamagata 992-8510, Japan
4. Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto Sumiyoshi-ku,
Osaka-shi 558-8585, Japan
5. Institute
of Laser Engineering, Osaka University,
2-6 Yamadaoka, Suita, Osaka 565-0871,
Japan
6. RIKEN, 519-1399, Aramaki-Aoba, Aoba-ku, Sendai 980-0845, Japan