Adaptive Stokes-Based Polarization Demultiplexing for Long-Haul Multi-Subcarrier Systems

We experimentally evaluate the performance of the adaptive Stokes polarization demultiplexing (PolDemux) algorithm over a long-haul optical link considering the propagation of $31\times 192$ Gb/s channels modulated as PM-16QAM multi-subcarrier (MSC) signals. Initially, we consider $1\times 24$ Gbaud channel under test, and subsequently, we assess the performance of the algorithm on an increasing number of subcarriers (up to $12\times 2$ Gbaud) while keeping the same aggregate symbol rate. Taking advantage of the higher robustness of MSC signals toward chromatic dispersion (CD), we demonstrate that the memoryless Stokes-based PolDemux algorithm, originally designed for short reach links, can also be used for low-complexity and modulation transparent polarization demultiplexing in long-haul systems. In addition, we demonstrate that the PolDemux rotation matrix for the MSC signals can be estimated over a restricted group of $N_{\mathrm {ref}}$ subcarriers and seamlessly applied to all $N_{\mathrm {sc}}$ subcarriers, thereby significantly reducing the overall complexity by a factor of $\sim \!\! N_{\mathrm {sc}} N_{\mathrm {sc}} / N_{\mathrm {ref}}$ .