A novel sparse Volterra model based fiber nonlinear equalization method for polarization-division-multiplexed CO-OFDM systems

In this paper, we address the challenges posed by fiber nonlinearity , specifically self-phase modulation (SPM) and cross-phase modulation (XPM), for a polarization-division-multiplexed coherent optical orthogonal frequency division multiplexing (PDM CO-OFDM) system using a novel sparse Volterra method. Though CO-OFDM combined with PDM offers high spectral efficiency and is a promising technology for next-generation optical communication , it is susceptible to fiber nonlinear effects . We introduced an improved sparse Volterra method, employing the orthogonal search approach to simplify the model’s coefficients. This approach helps manage the complexity associated with compensating nonlinear impact for PDM CO-OFDM system. Additionally, a multi-train sequence method is proposed to enhance the compensator’s effectiveness, especially in the context of wavelength-division multiplexing (WDM) systems. The designed compensator is validated through numerous simulations, and a comparative analysis of bit error rate (BER) performance is conducted, considering sparse Volterra compensator, 1-th order Volterra method, and 3-th order Volterra method. The results demonstrated the efficacy of the proposed sparse Volterra model in mitigating nonlinear effects with evidently reduced complexity.