[1] [1] Fei Wang, Xinliang Zhang and Yin Zhang, Opt. Commun. 284, 2337 (2011).

[2] [2] Zhengrong Tong, Mengying Liu and Ye Cao, Optoelectronics Letters 11, 326 (2015).

[3] [3] Guoyong Sun, Yingwu Zhou and Yihui Hu, IEEE Photonics Technology Letters 22, 766 (2010).

[4] [4] Zhigang Cao, Zhao Zhang and Tao shui, Optics & Laser Technology 56, 137 (2014).

[5] [5] Zhiyu Yan, Xiaohui Li and Yulong Tang, Optics Express 23, 4369 (2015).

[6] [6] Chenglai Jia, Xun Liang and Martin Rochette, IEEE Photonics Journal 7, 1 (2015).

[7] [7] Mingran Quan, Yuan Li and Jiajun Tian, Opt. Commun. 340, 63 (2015).

[8] [8] Azlan Sulaiman, Sulaiman Wadi Harun and Hamzah Arof, IEEE Journal of Quantum Electronics 48, 1165 (2012).

[9] [9] Xiaowei Ma, Chen Daru and Shi Qingguo, Journal of Lightwave Technology 32, 3234 (2014).

[10] [10] R.Selvas-Aguilar, A.Martínez-Rios and G.Anzueto- Sánchez, Optical Fiber Technology 20, 391 (2014).

[11] [11] M. I. Md Ali, S. A. Ibrahim and M. H. Abu Bakar, IEEE Photonics Journal 6, 1 (2014).

[12] [12] Zhibo Liu, Yang Li and Yan Liu, IEEE Photonics Technology Letters 25, 2050 (2013).

[13] [13] Xiaowei Ma, Daru Chen and Qingguo Shi, Journal of Lightwave Technology 32, 3234 (2014).

[14] [14] R. Selvas-Aguilar, A. Martínez-Rios and G. Anzueto- Sánchez, Optical Fiber Technology 20, 391 (2014).

[15] [15] Guolu Yin, Shuqin Lou and Ping Hua, IEEE Photonics Technology Letters 26, 2279 (2014).

[16] [16] Ye Cao, Lei Chen and Nan Lu, Journal of Optoelectronics ·Laser 26, 9 (2015). (in Chinese)

[17] [17] Panpan Luan, Zhengrong Tong and Ye Cao, Optical Engineering 54, 087106 (2015).

[18] [18] Zhengrong Tong, Xia Hao and Ye Cao, Opt. Commun. 335, 78 (2015).