1. Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, N2L 3G1 ON, Canada
2. Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, P. R. China
3. Department of Systems Design Engineering, University of Waterloo, 200 University Avenue, Waterloo, N2L 3G1 ON, Canada
4. Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France
5. Department of Electrical and Computer Engineering, University of Waterloo, 200 University Avenue, Waterloo, N2L 3G1 ON, Canada
6. School of Physics and Electronics, Henan University, No. 1 Jinming Street, Kaifeng, Henan, P. R. China