1. Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University 1 , Guangzhou 510006, China
2. Department of Applied Physics, Hong Kong Polytechnic University 2 , Hong Kong, China
3. School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University 3 , Tianjin 300350, China
4. Laboratory of Solid-State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University 4 , Nanjing 210093, China