1. School of Physics and Optoelectronic Engineering Guangdong University of Technology Guangzhou 510006 P. R. China
2. Institute of Photoelectronic Thin Film Devices and Technology Nankai University Tianjin 300350 P. R. China
3. Guangdong Provincial Key Laboratory of Information Photonics Technology Guangdong University of Technology Guangzhou 510641 P. R. China
4. State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques South China University of Technology Guangzhou 510641 P. R. China
5. School of Basic Medical Sciences Guangzhou Medical University Guangzhou 510182 P. R. China