1. State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
2. Photonics Laboratory, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
3. Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong