1. Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
2. Center for Disruptive Photonic Technologies The Photonics Institute Nanyang Technological University Singapore 639798 Singapore
3. Institute of Microelectronics Agency for Science Technology and Research (A*STAR) Singapore 138634 Singapore
4. Laboratoire de Physique des Lasers Atomes et Molécules PhLAM Université de Lille CNRS UMR 8523 Villeneuve d'Ascq 59655 France
5. Université de Lille CNRS Centrale Lille Univ. Polytechnique Hauts‐de‐France IEMN—Institut d'Electronique de Microélectronique et de Nanotechnologie UMR 8520 Villeneuve d'Ascq 59652 France