1. College of Physics and Electronic Engineering, Chongqing Normal University 1 , Chongqing 401331, China
2. School of Electronic Science and Applied Physics, Hefei University of Technology 2 , Hefei, Anhui 230009, People's Republic of China
3. Key Laboratory of Optoelectronic Technology and Systems (Ministry of Education), College of Optoelectronic Engineering, Chongqing University 3 , Chongqing 400044, China
4. College of Engineering and Applied Sciences, Nanjing University 4 , Nanjing 210093, China
5. College of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications 5 , Chongqing 400065, China