[1] [1] D. Gregory, W. Van, and R. Rajarshi, Science 279, 1198 (1998).

[2] [2] M. Digonnet, Rare Earth-Doped Fiber Lasers and Amplifiers (Marcel Dekker, New York, 1993).

[3] [3] M. A. Putnam, M. L. Dennis, I. N. Duling III, C. G. Askins, and E. J. Friebele, Opt. Lett. 23, 138 (1998).

[4] [4] Y. Cheng, J. T. Kringlebotn, W. H. Loh, R. I. Laming, and D. N. Payne, Opt. Lett. 20, 875 (1995).

[5] [5] K. Zhang and J. U. Kang, Opt. Express 16, 14173 (2008).

[6] [6] X. Yang, L. Zhan, Q. Shen, and Y. Xia, IEEE Photon. Technol. Lett. 20, 879 (2008).

[7] [7] H. Qi, J. Zhang, G. Zhou, A. Wang, and Z. Zhang, Chin. Opt. Lett. 11, 061402 (2013).

[8] [8] S. J. Tan, S. W. Harun, H. Arof, and H. Ahmad, Chin. Opt. Lett. 11, 073201 (2013).

[9] [9] L. G. Luo, T. J. Tee, and P. L. Chu, J. Opt. Soc. Am. B 15, 972 (1998).

[10] [10] F. Zhang, P. L. Chu, R. Lai, and G. R. Chen, IEEE Photon. Technol. Lett. 17, 549 (2005).

[11] [11] F. Chang, Y. Feng, Z. Yao, J. Fan, Y. Song, and Y. Zhao, Chin. Phys. B 21, 100504 (2012).

[12] [12] Y. Liu, X. Feng, W. Zhang, and X. Liu, Chin. Phys. B 18, 3318 (2009).

[13] [13] L. Yang, L. Zhang, R. Yang, L. Yang, B. Yue, and P. Yang, Opt. Commun. 285, 143 (2012).

[14] [14] W. Fan, X. Tian, J. Chen, F. Zheng, Y. Yu, B. Gao, and H. Luo, Chin. Phys. 16, 2908 (2007).

[15] [15] S. Zhang, H. Yang, and X. Qian, Acta Phys. Sin. 53, 3706 (2004).

[16] [16] A. Dandridge, A. B. Tveten, and T. G. Giallorenzi, IEEE J. Quantum Electron. 18, 1647 (1982).

[17] [17] D. Brunner, X. Porte, M. C. Soriano, and I. Fischer, Sci. Rep. 2, 732 (2012).

[18] [18] D. J. DeShazer, J. Garcia-Ojalvo, and R. Roy, Phys. Rev. E 67, 036602 (2003).