[1] 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. 8, 1442 (1997).
[2] J. Wang, Y. Rao, and T. Zhu, Chinese J. Lasers (in Chinese) 34, 389 (2007).
[3] X. Luo, Y. Rao, and Z. Ran, Acta Opt. Sin. (in Chinese) 27, 1393 (2007).
[4] R. Li, Y. Yu, W. Dai, and S. Liu, Acta Opt. Sin. (in Chinese) 27, 1950 (2007).
[5] Z. Zhang, M. Zhang, and P. Ye, Chinese J. Lasers (in Chinese) 33, 1073 (2006).
[6] J. Mandal, Y. Shen, S. Pal, T. Sun, K. T. V. Grattan, and A. T. Augousti, Opt. Commun. 244, 111 (2005).
[7] Y. Yu, L. Lui, H. Tam, and W. Chung, IEEE Photon. Technol. Lett. 13, 702 (2001).
[8] S. M. Melle, A. T. Alavie, S. Karr, T. Coroy, K. Liu, and R. M. Measures, IEEE Photon. Technol. Lett. 5, 263 (1993).
[9] X. Yang, S. Luo, Z. Chen, J. H. Ng, and C. Lu, Opt. Commun. 271, 203 (2007).
[10] L.-Y. Shao, X. Dong, A. P. Zhang, H.-Y. Tam, and S. He, IEEE Photon. Technol. Lett. 19, 1598 (2007).
[11] X. Yang, C.-L. Zhao, Q. Peng, X. Zhou, and C. Lu, Opt. Commun. 250, 63 (2005).
[12] N. J. C. Libatique and R. K. Jain, IEEE Photon. Technol. Lett. 13, 1283 (2001).
