1. Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
2. International Joint Research Center for Nanophotonics and Biophotonics, Changchun, Jilin 130022, China
3. School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore