Digital Back Propagation Algorithm for Nonlinear Compensation in 54.5GBaud 4000km 16QAM Raman Amplification Transmission System

In this paper, a digital back propagation (DBP) nonlinearity compensation algorithm is proposed and experimentally investigated over backward-pumped Raman amplified 4000-km fiber links employing 54.5-GBaud 16-ary quadrature amplitude modulation (16-QAM). By utilizing DBP for Raman amplification, significant improvements are achieved. The Q-factor shows an enhancement of 0.83 dB, and the optimal launch power is improved by 3 dBm. These results highlight the effectiveness of DBP in mitigating nonlinear impairments and optimizing the performance of Raman amplification systems.