1. Key Laboratory of Optoelectronic Technology & Systems, Ministry of Education, and College of Optoelectronic Engineering , 47913 Chongqing University , Chongqing 400044 , China
2. School of Optoelectronic Engineering , Guangdong Polytechnic Normal University , Guangzhou 510665 , China
3. College of Physics and Information Engineering , Minnan Normal University , Zhangzhou 363000 , China
4. School of Electrical and Electronic Engineering , Nanyang Technological University , Singapore 639798 , Singapore