1. Institute of Optical and Electronic Technology, China Jiliang University, Hangzhou 310018, P. R. China
2. School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China
3. School of Physics, Southeast University, Nanjing 211189, P. R. China
4. Key Laboratory of Ecophysics and Department of Physics, Shihezi University, Xinjiang 832003, P. R. China
5. College of Physical Science and Technology, Nanjing Normal University, Nanjing 210023, P. R. China