1. Key
Laboratory of Optical Fiber Sensing and Communications (Education
Ministry of China), University of Electronic Science and Technology of China, Chengdu 610054, China
2. Fang
Lu Mesoscopic Optics and Quantum Electronics Laboratory, University of California, Los Angeles, California 90095, United States
3. Cambridge
Graphene Center, University of Cambridge, Cambridge CB3 0FA, United Kingdom
4. Department
of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
5. State
Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China