1. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
2. A*STAR Institute of High Perfomance Computing, Singapore 138632, Singapore
3. Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
4. School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore