1. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
2. School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China
3. School of Materials Science and Engineering, Nanyang Technological University, Singapore 637371, Singapore
4. Department of Physics, Tezpur University (Central University), Tezpur 784028, India
5. The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371, Singapore
6. Center for Quantum Technologies, National University of Singapore, Singapore 119077, Singapore