1. College of Electronic Science & Engineering, Jilin University, 2699 Qianjin Street, Changchun130012, P. R. China
2. State Key Laboratory of High Power Semiconductor Lasers, School of Science, Changchun University of Science and Technology, 7089 Wei-Xing Road, Changchun130022, P. R. China
3. Changchun University of Science and Technology Chongqing Research Institute, 618 Liangjiang Road, Chongqing130022, P. R. China
4. Institute of Semiconductors, Chinese Academy of Sciences, Beijing100083, P.R. China