Research On Signal Processing Algorithms Of Stokes Vector Receiver For Short-reach Optical Interconnection

Emerging forms of video streaming,cloud computing,embedded security,machine learning,artificial intelligence and the Internet of things are driving the growth of the telecommunications and data communications markets.With the explosive increase of communication data,there is a rate bottleneck in the efficient interconnection between data centers.In order to improve the speed of the data center,the short-distance optical interconnection transmission is highly concerned.At present,direct detection system plays a dominant role in the interconnection of short-reach optical transmission.However,the rapid growth of data capacity demand pushes the short-reach capacity to 100 G and 400 G,and the traditional one-dimensional direct detection system can no longer meet the demand of short-reach capacity.Considering the low cost,large transmission capacity and high signal spectrum utilization of short-reach optical interconnection,this paper mainly studies the signal processing algorithm based on Stokes Vector Direct Detection scheme between direct detection and coherent detection.This scheme supports polarization multiplexing of transmitter signals and realizes the system based on carrier and signal and PAM and QAM polarization multiplexing.The polarization multiplexing of PAM and QAM realizes the 3-D modulation of signal and improves the transmission capacity and spectrum efficiency.In this paper,stokes vector receiver is combined with digital signal processing technology to make it one of the most promising transmission schemes in short-reach optical interconnection.In order to improve the performance of stokes vector receiver,the polarization state,polarization dependent loss and dispersion effect tracking compensation technology based on carrier and signal and PAM and QAM polarization multiplexing transmission system are studied.The error rate of the recovered signal,the signal-to-noise cost of the system and the polarization rate tolerance are used as the main evaluation criteria of the tracking technology.Stokes vector receiving signal processing of PDM SC-m QAM SV-DD transmission system mainly includes random polarization state tracking,polarization dependent loss and dispersion compensation.Stokes vector receiving signal processing of PDM PAM-QAM SV-DD transmission system is mainly random polarization state tracking.In PDM SC-m QAM SV-DD system,based on Extended Kalman Filter and Particle Filter polarization tracking technology are proposed.In high-capacity transmission systemextended kalman filter technology realizes RSOP tracking in high-order modulation format.Numerical simulation shows that extended kalman filter technology has high tolerance of polarization rotation rate and lower signal-to-noise ratio cost.The polarization rotation rate tolerance of the particle filter is much higher than that of LMS and EKF,and it has a high tracking accuracy and a fast convergence speed,at a low signal-to-noise ratio cost.MIMO technology based on least square method is proposed for the random polarization state in PDM PAM-QAM SV-DD transmission system.Numerical simulation shows that the algorithm has high polarization tolerance and good tracking stability at low signal-to-noise ratio cost.In the PDM SC-m QAM SV-DD transmission system,blind adaptive and Extended Kalman Filter technologies are proposed for random polarization states and polarization dependent losses.Both of these algorithms reduce the algorithm complexity of stokes vector receiver.The numerical results show that the blind adaptive algorithm can track the polarization correlation loss and random polarization state stably even under high speed polarization rotation.However,it's of tracking performance is poor for higher-order modulation format.Therefore,a polarization state and polarization dependent loss cooperative tracking technique based on extended kalman filter is proposed.Compared with blind adaptive algorithm,extended kalman filter has lower signal-to-noise ratio cost,and it can track polarization state and polarization dependent loss in time-varying channel stably and quickly even in high-order modulation format.In the PDM SC-m QAM SV-DD transmission system,based on stokes space extended kalman filter of the mean power decision and dorsal transmission joint compensation techniques have been proposed.Numerical results show that this scheme has a high tolerance for random polarization state and a good tracking stability in the presence of dispersion.