1. College of Integrated Circuit Science and Engineering, Nanjing University of Posts and Telecommunications , Nanjing , 210023 , China
2. School of Information Science and Technology, Fudan University , Shanghai 200433 , China
3. Department of Photonics and Graduate Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University , Hsinchu , 30010, Taiwan , China
4. Semiconductor Research Center, Hon Hai Research Institute , Taipei , Taiwan , China