1. Department of Optoelectronic Science
2. Harbin Institute of Technology at Weihai
3. Weihai 264209
4. China
5. School of Materials Science and Engineering
6. Nanyang Technological University
7. Singapore 639798
8. Singapore
9. School of Marine Science and Technology
10. State Key Laboratory of Urban Water Resource & Environment
11. Division of Physics and Applied Physics
12. School of Physical and Mathematical Sciences
13. Singapore 637616
14. Department of Physics
15. Sichuan University
16. Chengdu 610064