[1] N. Y. Kim, J. Park, H. Kim, and N. Park, in Proceedings of OFC2002 W16, 239

[2] M. C. Parker, in Proceedings of OFC2002 THGG56, 691 (2002).

[3] E. Corbel, in Proceedings of OFC2002 TuN1 (Invited), 35 (2002).

[4] Y. D. Gong, Ph. D. Dissertation of Beijing Jiaotong University (Mar. 16, 1998).

[5] M. G. Wang, T. J. Li, and S. S. Jian, Opt. Express 11, 2354 (2003).