1. Guangdong Provincial Key Laboratory of Information Photonics Technology, School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong, P. R. China
2. School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, China
3. School of Semiconductor Science and Technology, South China Normal University, Foshan 528225, Guangdong, P. R. China
4. State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials Science & Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, P. R. China
5. The Basic Course Department, Guangzhou Maritime University, Guangzhou 510799, Guangdong, P. R. China
6. College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, Zhejiang, P. R. China