1. State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
2. Next Generation Internet Access National Engineering Lab (NGIA), School of Optical and Electronic Information, Huazhong University of Sci&Tech (HUST), 1037 Luoyu Road, Wuhan 430074, China
3. Yangtze Optical Fibre and Cable Joint Stock Limited Company, State Key Laboratory of Optical Fiber and Cable Manufacture Technology, Wuhan 430073, China