1. School of Information and Communication Engineering University of Electronic Science and Technology of China Chengdu 611731 China
2. Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory University of California Los Angeles CA 90095 USA
3. Optical Nanostructures Laboratory Columbia University New York NY 10027 USA
4. Institute of Microelectronics A*STAR Singapore 117865
5. Brookhaven National Laboratory Upton NY 11973 USA
6. Johns Hopkins Applied Physics Laboratory Laurel MD 20723 USA