1. Division of Physics and Applied PhysicsSchool of Physical and Mathematical SciencesNanyang Technological University 21 Nanyang Link Singapore 637371 Singapore
2. Centre for Disruptive Photonic TechnologiesThe Photonic Institute 50 Nanyang Avenue Singapore 639798 Singapore
3. NUSNNI‐NanoCoreNational University of Singapore Singapore 117411 Singapore
4. NUS Graduate School for Integrative Science and EngineeringNational University of Singapore Singapore 117456 Singapore
5. Department of PhysicsNational University of Singapore Singapore 117542 Singapore
6. Department of Electrical and Computer EngineeringNational University of Singapore Singapore 117583 Singapore
7. Department of Materials Science and EngineeringNational University of Singapore Singapore 117575 Singapore