1. Department of Applied Physics School of Advanced Engineering and Graduate School of Engineering Kogakuin University 2665-1 Nakano, Hachioji Tokyo 192-0015 Japan
2. Department of Electronic Science and Engineering Kyoto University Nishikyo-ku Kyoto 615-8510 Japan
3. Engineering Education Research Center Kyoto University Nishikyo-ku Kyoto 615-8530 Japan
4. Photonics and Electronics Science and Engineering Center Kyoto University Nishikyo-ku Kyoto 615-8520 Japan