[1] Z. Meng, Y. M. Hu, S. D. Xiong, Y. Liu, M. Ni, and X. L. Zhang, Chin. J. Lasers (in Chinese) 29, 415 (2002).

[2] L. Xia, X. H. Li, Y. Z. Yin, J. Feng, J. Mao, X. F.Chen, and S. H. Xie, Acta Opt. Sin. (in Chinese) 22, 1004 (2002).

[3] S. H. Yuan, Q. Hu, and M. Q. Wang, Acta Opt. Sin. (in Chinese) 22, 383 (2002).

[4] J. Noda, K. Okamoto, and Y. Sasaki, J. Lightwave Technol. 4, 1071 (1986).

[5] Y. L. Ruan, Q. Xiang, and D. X. Huang, Chin. J. Lasers (in Chinese) 23, 901 (1996).

[6] K.-H. Tsai, K.-S. Kim, and T. F. Morse, J. Lightwave Technol. 9, 7 (1991).

[7] Y. A. Liu and B. M. A. Rahman, J. Lightwave Technol. 13, 142 (1995).

[8] C. S. Chang and H. C. Chang, J. Lightwave Technol. 15, 1213 (1997).

[9] K. Dossou, S. L. Rochelle, and M. Fontaine, J. Lightwave Technol. 20, 1463 (2002).

[10] L. Li and Y. Q. Huang, Fundamental of Optical Fiber Communication (in Chinese) (National Defense Industry Press, Beijing, 1992) p.120.

[11] P. L. Chu and R. A. Sammut, J. Lightwave Technol. 2, 650 (1984).

[12] Y. M. Hu, Z. Chen, Y. B. Liao, S. L. Chang, J. C. Tan and Z. Meng, Chin. J. Lasers (in Chinese) 25, 716 (1998).

[13] X. D. Zeng and Y. Y. An, Semiconductor Optoelectronics (in Chinese) 20, 312 (1999).