1. Research Center for Development of Far Infrared Region, University of Fukui, Fukui 910-8507
2. Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 229-8558
3. Department of Physics, Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550
4. Department of Chemistry, Faculty of Science, Hiroshima University, Higashihiroshima, Hiroshima 739-8526
5. International Institute for Advanced Studies, Kizugawa, Kyoto 619-0225