1. National Laboratory of Solid State Microstructures
2. Collaborative Innovation Center of Advanced Microstructures
3. School of Electronic Science and Engineering
4. Nanjing University
5. Nanjing 210093
6. State Key Laboratory of Surface Physics and Department of Physics
7. Fudan University
8. Shanghai 200433
9. China
10. College of Engineering and Applied Sciences
11. Shenzhen Key Laboratory of Laser Engineering
12. College of Optoelectronic Engineering
13. Shenzhen University
14. Shenzhen 518060
15. School of Physics