Analysis of Influence of Polarization Mode Dispersion on Tb/s Single-Carrier Coherent Optical Fiber Communication Systems

In ultrahigh-speed coherent optical fiber communication systems, increasing single-carrier data rate is usually considered the foundation for the data rate increase of wavelength division multiplexing (WDM) communication systems. In single-carrier optical fiber communication systems, polarization mode dispersion (PMD) is one of the most critical factors affecting the data rate increase. This article quantitatively analyzed the impact of first-order, second and higher-order, full-order PMD on coherent fiber communication systems at the single-carrier bit rate of Tb/s levels from the perspective of error vector magnitude and symbol error rate (EVM/SER). The constant modulus algorithm (CMA) was analyzed for PMD compensation performance. Finally, the optimal tap numbers of the CMA were calculated in three cases of PMD. The results show that the optical signal-to-noise ratio (OSNR) tolerance limit can be improved by 6.7 dB and 6 dB, respectively, in first-order PMD and second and higher-order PMD. SER and EVM in second and higher-order PMD are almost 100% and 99.36% better than in first-order PMD, given the compensation performance of CMA. The optimal tap numbers of CMA differ in three cases of PMD.