RSOP equalization through a single polarization constant modulus scheme in optical coherent communication systems

The adoption of high-speed optical fiber communication is essential for enhancing reliability and capacity in recent years. However, lightning-induced rapid state-of-polarization (RSOP) fluctuations pose significant challenges, leading to increased bit error rates and potential communication failures. Existing mitigation techniques—including optical-domain polarization diversity, Stokes-space processing, and electrical-domain digital signal processing—suffer from limitations such as high complexity, limited tracking speed, or lack of generality. This paper proposes a parallel constant modulus algorithm (CMA) based on single-polarization transmission to overcome these issues. By leveraging the direct relationship between the IQ phase difference and SOP variations, the method eliminates polarization crosstalk and maintains low computational complexity. Simulation results demonstrate that the proposed approach achieves an ultra-fast RSOP tracking capability of up to 20 Mrad/s at a transmission rate of 100 Gbit/s, offering a robust and efficient solution for polarization impairment compensation in high-speed optical communication systems.