1. Institute of Microelectronics and Beijing National Research Center for Information Science and Technology (BNRist) Tsinghua University Beijing 100084 China
2. School of Electrical Engineering and State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing University Chongqing 400044 China
3. College of Optoelectronic Engineering and Key Laboratory of Optoelectronic Technology & Systems Education Ministry of China Chongqing University Chongqing 400044 China