1. State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, and Guangdong Engineering Technology Research Center of Special Optical Fiber Materials and Devices, South China University of Technology, Guangzhou 510641, China
2. Guangdong Provincial Key Laboratory of Information Photonics Technology, School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China