Institute of Optics and Electronic Imformation;
Huazhong University of Science and Technology;
Wuhan;
China;
School of Electronic and Imformation Engineering;
Huazhong University of Science and Technology;
Wuhan;
China;
National Engineering Laboratory for Next Generation Internet Acess System;
Wuhan;
China;
Joint; Phase; Noise; Estimate; Fiber; Nonlinearity; PDM-4QAM; Optimum; Launch; Power; Phase; Noise; Compensation;