Enhanced Optical Phase Conjugation Technique for Fiber Nonlinearity Mitigation by Two-Stage Optimization

One of the hottest subjects in the current optical communication sector is the use of optical phase conjugation (OPC) method to decrease fiber nonlinearity. To enhance OPC's capacity to suppress fiber nonlinearity, we propose a two-stage optimization strategy for maximizing the power of conjugated signals and the cumulative dispersion of conjugated signals for the dispersion-managed optical transmission link of erbium-doped fiber amplifiers. The theoretical analysis reveals that the performance gain brought by power optimization is only related to the dispersion-attenuation coefficient ratio of the fiber. Therefore, the theoretical analysis findings are validated using two types of dispersion management connections as examples: super-large-area fiber and inverse dispersion fiber (SLA-IDF) and standard single-mode fiber and dispersion compensation fiber (SSMF-DCF). The numerical simulation results show that after the 9-channel polarization multiplexed quadrature-phase-shift keying signal is transmitted over 1920 km (24x80 km), for the SLA-IDF link, the optimal signal-to-noise ratio (SNR) of the system after optimizing the optical intensity and dispersion is improved by 3.8 dB and 1.0 dB, respectively; for the SSMF-DCF link, the optimal SNR of the system after optimizing the optical intensity and dispersion is improved by 0.4 dB and 1.6 dB , respectively.