1. Wuhan National Laboratory for Optoelectronics
2. School of Optical and Electronic Information
3. Huazhong University of Science and Technology
4. Wuhan 430074
5. China
6. Department of Physics
7. National Sun Yat-Sen University
8. Kaohsiung 80424
9. Taiwan
10. School of Chemistry and Chemical Engineering
11. Shanghai Jiao Tong University
12. Shanghai 200240