1. Department of Electronics, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
2. Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, 38042 Grenoble, CEDEX 9, France
3. Department of ECE, Cornell University, 415 Phillips Hall, Ithaca, NY 14853, U.S.A.
4. School of Physical Sciences, The Graduate University for Advanced Studies, Okazaki, Aichi 444-8585, Japan
5. UVSOR Facility, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
6. Department of Electrical and Electronics Engineering, University of Fukui, Fukui 910-8507, Japan