1. Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
2. Key Laboratory of Optical Monitoring Technology of Environment, Anhui Institute of Optics and Fine Mechanics, Hefei 230031, China
3. School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei 230026, China
4. Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China