1. School of Optics and Photonics , Beijing Institute of Technology , Beijing 100081 , China
2. Department of Electronic Engineering , 12442 Tsinghua University , Beijing 100084 , China
3. Key Laboratory of Photoelectronic Imaging Technology and System, Ministry of Education of China , Beijing 100081 , China
4. Beijing Institute of Technology Chongqing Innovation Center , Chongqing 401135 , China