1. State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices South China University of Technology Guangzhou 510641 P. R. China
2. MOE Key Laboratory of Bioinorganic and Synthetic Chemistry KLGHEI of Environment and Energy Chemistry School of Chemistry Sun Yat‐sen University Guangzhou 510006 P. R. China
3. School of Physics and Optoelectronics South China University of Technology Guangzhou 510641 P. R. China