1 Photonics Laboratory, Computer, Electrical and Mathematical Sciences and Engineering Division (CEMSE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
2 Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
3 Light Source Research Division, Korea Photonics Technology Institute (KOPTI), Gwangju 61007, Republic of Korea
4 School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
5 Department of Advanced Convergence Technology, Research Institute of Advanced Convergence Technology, Korea Polytechnic University, 237 Sangidaehak-ro, Siheung-si 15073, Republic of Korea
6 King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia