1. K. Sato, S. Okamoto and H. Hadama: IEEE J. Sel. Areas Commun. 12 (1994) 159.
2. M. Koga, A. Watanabe, S. Okamoto, K. Sato, H. Takahashi and M. Okuno: European Conf. Optical Communications, 1996, Paper ThC.3.1.
3. M. Koga and A. Watanabe: Proc. 15th Annual Meet. of the IEEE Laser & Electro-Optics Society, 2002, Vol. 2, Paper WF1, p. 405.
4. H. Ishio, J. Minowa and K. Nosu: IEEE J. Lightwave Tech. 2 (1984) 448.
5. H. Masuda: Proc. Optical Fiber Communication, 2000, Paper TuA1-1