1. School of Physics, Beihang University, Beijing 100191, China
2. Institute of New Energy Materials and Devices, Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China
3. Institute of Laser Engineering, Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 999077, China
4. Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon 518057, Hong Kong, China