1. Beijing
Engineering Research Center of Mixed Reality and Advanced Display,
School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China
2. Department of Physics and Materials Science & Center for Functional Photonics (CFP), City University of Hong Kong, Hong Kong S. A. R.
3. Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing 100081, China
4. Department
of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong S. A. R.