1. College of Mathematics and Physics, Beijing University of Chemical Technology , Beijing 100029 , China
2. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 637371 , Singapore
3. Institute of Physical Science and Information Technology, Anhui University , Hefei 230601 , China
4. Research Laboratory for Quantum Materials, Singapore University of Technology and Design , Singapore 487372 , Singapore
5. School of Materials Science and Engineering, Nanyang Technological University , Singapore 639798 , Singapore
6. CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology , Beijing 100190 , China
7. The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University , Singapore 637371 , Singapore