1. Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Materials Science & Engineering, Beijing Institute of Technology, 5 Zhongguancun South Street, Beijing 100081, China
2. State
Key Laboratory of Luminescence and Applications, Changchun Institute
of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
3. Key
Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004, China
4. Micro/Nano
Research Center, School of Physics, Beijing Institute of Technology, 5 Zhongguancun South Street, Beijing 100081, China