[1] [1] Li Hong-cai, Liu Chun-tong, Feng Yong-bao, Zhou Zhao-fa and He Zhen-xin, Journal of Optoelectronics ·Laser 26, 309 (2015). (in Chinese)

[2] [2] Bian Ji-cheng, Lang Ting-ting, Yu Wen-jie and Kong Wen, Journal of Optoelectronics·Laser 26, 2169 (2015). (in Chinese)

[3] [3] S. J. Feng, Q. H. Mao, Y. Y. Tian and Y. Ma, IEEE Photonics Technology Letters 25, 323 (2013).

[4] [4] Y. Wei, K. Hu, B. Sun and T. Wang, Laser Physics 22, 770 (2012).

[5] [5] R. E. Nu ez-Gomez, G. Anzueto-Sanchez, A. Martinez- Rios, M. A. Basurto-Pensado, J. Castrellon-Uribe, R. Selvas-Aguilar, J. Camas-Anzueto and V. M. Duran- Ramirez, Optical Review 22, 526 (2015).

[6] [6] T. Feng, P. F. Yan, Q. Li, W. J. Peng, S. Y. Tan, S. C. Feng, P. Liu and X. D. Wen, Laser Physics 23, 025101 (2013).

[7] [7] J. Masson, R. St-Gelais, A. Poulin and Y. A. Peter, IEEE Journal of Quantum Electronics 46, 1313 (2010).

[8] [8] V. Serbezov, S. Sotirov, K. Benkhouja, A. Zawadzka and B. Sahraoui, Optical Material 36, 53 (2013).

[9] [9] Wei Yang, Ying Liu, Lifeng Xiao and Zhaoxiang Yang, Journal of Lightwave Technology 28, 118 (2010).

[10] [10] Ping Yi, Biao Liu, Dan Zhou, Song Yang and Zhong Ye, Piezoelectrics & Acoustooptics 36, 552 (2014). (in Chinese)

[11] [11] H. K. Hisham, A. F. Abas, G. A. Mahdiraji, M. A. Mahdi and F. R. M. Adikan, Optical Review 22, 278 (2015).

[12] [12] Wei Shi, Qiang Fang, Yang Xu, Yuguo Qin, Jingli Fan, Xiangjie Meng and Qihang Zhang, Journal of Optoelectronics ·Laser 26, 662 (2015). (in Chinese)

[13] [13] Qing-Yao Wan, Bao-Jian Wu, Xing-Yu Zhou and Feng Wen, Optical Fiber Technology 24, 89 (2015).

[14] [14] Nair Anitha S., Kumar V. P. Sudeep and Joe Hubert, Applied Optics 54, 2007 (2015).

[15] [15] S. L. Pan and J. P. Yao, IEEE Photonics Technology Letters 22, 413 (2010).

[16] [16] Yanxing Ma, Pu Zhou, Xiaolin Wang, Haotong Ma, Xiaojun Xu, Lei Si, Zejin Liu and Yijun Zhao, Optics Letter 35, 1308 (2010).

[17] [17] Guoyu Li, Kang Yang, Sumei Jia, Yan Li and Mingsheng Liu, Acta Optica Sinica 35, 0614003 (2015). (in Chinese)

[18] [18] Y. Takeuchi, Applied Optics 35, 1478 (1996).

[19] [19] W. Shin, S. Choi and K. Oh, Optics Letter 27, 1884 (2002).