[1] [1] Yi Li, Edouard Harris, Liang Chen and Xiaoyi Bao, Optics Express 18, 8135 (2010).

[2] [2] Chieh J. J., Yang S. Y., Chao Y. H., Horng H. E., Hong Chin Yih and Yanf H. C., Journal of Applied Physics 97, 043104 (2005).

[3] [3] Ye Cao, Huiying Liu, ZhengrongTong, Shuo Yuan and Shun Zhao, Optoelectronics Letters 11, 69 (2015).

[4] [4] Ye Cao, Wen Liu, Shun Zhao, ZhengrongTong and Huiying Liu, Journal of Optoelectronics·Laser 26, 1233 (2015). (in Chinese)

[5] [5] Ting Liu, Xianfeng Chen, Ziyun Di, Junfeng Zhang and Jianping Chen, Applied Physics Letters 91, 121116 (2007).

[6] [6] Qi Li, Kaiqiang Huang and Haiyan Chen, Optoelectronics Letters 11, 466 (2015).

[7] [7] Binbin Song, Yinping Miao, Wei Lin, Hao Zhang, Bo Liu, Jixuan Wu, Haifeng Liu and Donglin Yan, IEEE Photonics Technology Letters 26, 2283 (2014).

[8] [8] Chao Li, Tigang Ning, Xiaodong Wen, Jing Li, Chan Zhang and Chuanbiao Zhang, Optics & Laser Technology 72, 104 (2015).

[9] [9] Salceda-Delgado G., Monzon-Hernandez D., Martinez- Rios A., Cardenas-Sevilla G. A. and Villatoro J., Optics Letters 37, 1974 (2012).

[10] [10] Jicheng Bian, Tingting Lang, Wenjie Yu and Wen Kong, Journal of Optoelectronics·Laser 26, 2169 (2015). (in Chinese).

[11] [11] Peng Zu, Chichiu Chan, Wensiang Lew,Yongxing Jin, Yifan Zhang, Hwifen Liew, Lihan Chen, Weichang Wong and Xinyong Dong, Optics Letters 37, 398 (2012).