1. Hamamatsu Photonics K. K., 5000, Hirakuchi, Hamakita-ku, Hamamatsu, Shizuoka 434-8601
2. Institute of Laser Engineering, Osaka University, 2-6, Yamada-oka, Suita, Osaka 565-0871
3. Graduate School of Engineering, University of Fukui, 3-9-1, Bunkyou, Fukui 910-8507