1. School of Physics and Optoelectronics, State Key Laboratory of Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou, China
2. School of Physics and Optoelectronics, State Key Laboratory of Luminescent Materials and Devices and Institute of Optical Communication Materials, Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices, Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China