State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China

Department of Electrical Engineering, Faculty of Electrical and Computer Engineering, Shahid Beheshti University, Tehran 1983963113, Iran

School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China

¹ Tsinghua National Laboratory for Information Science and Technology (TNList), Department of Electrical Engineering, Tsinghua University, Beijing 100084, China

² The Photonic Systems Research Laboratory, Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China

Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong, China

AT&T Labs-Research, Middletown, NJ 07748, USA

The State Key Lab of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240 China

Tsinghua National Laboratory for Information Science and Technology, State Key Laboratory of Integrated Optoelectronics, Department of Electronics, Tsinghua University, Beijing 100084, China

¹ The TeCIP Institute of Scuola Superiore Sant’Anna di Pisa, via G. Moruzzi 1, 56124 Pisa, Italy

² Centre d'optique, photonique et laser, 2375 rue de la Terrasse, local 2104, Université Laval, Québec, G1V 0A6, Canada

³ CNIT, via G. Moruzzi 1, 56124 Pisa, Italy

Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK

¹ The Institute of Optics, University of Rochester, Rochester, NY 14627, USA

² Department of Engineering Physics, école Polytechnique de Montréal, Montréal, QC H3C 3A7, Canada

Photonic Device Research Laboratory (PDRL), Beijing University of Technology, Beijing 100124, China