[1] T. Erdogan, J. Lightwave Technol. 15, 1277 (1997).

[2] Y. Zhan, S. Xue, and Q. Yang, Chin. Opt. Lett. 5, 135 (2007).

[3] R. Li, Y. Yu, W. Dai, and S. Liu, Acta Opt. Sin. (in Chinese) 27, 1950 (2007).

[4] J. Yang and L. Yuan, Chinese J. Lasers (in Chinese) 32, 1391 (2005).

[5] A. D. Kersey, M. A. Davis, H. J. Patrick, M. LeBlanc, K. P. Koo, C. G. Askins, M. A. Putnam, and E. J. Friebele, J. Lightwave Technol. 15, 1442 (1977).

[6] W. Wang, J. Yu, X. Fu, and E. Yang, Acta Opt. Sin. (in Chinese) 26, 1304 (2006).

[7] S. Abbenseth and S. I. Lochmann, in Proceedings of Journal of Physics: Conference Series 15, 149 (2005).