1 School of Optoelectronic Information, University of Electronic and Science Technology of China, Chengdu 610054, CHN
2 Key Laboratory of Broadband Optical Fiber Transmission and Communication Network, Ministry of Education of China, University of Electronic and Science Technology of China, Chengdu 610054, CHN
Institute of Electronic Information and Control Engineering, Beijing Optoelectronic Technology Lab, Beijing University of Technology, Beijing 100022, CHN