1. Harvard Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
2. Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
3. Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
4. University of Waterloo, Waterloo, ON N2L 3G1, Canada
5. NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, China
6. SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Shenzhen University, Shenzhen 518060, China