1. College of Electronics and Information Engineering, Sichuan University, Chengdu, Sichuan, China
2. Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China
3. Key Lab of Optical Fiber Sensing and Communications, University of Electronic Science and Technology of China, Chengdu, Sichuan, China