Optical Phase Conjugation Outperforms Digital Backpropagation in 50-GBPS DWDM Systems: EVM and FWM Suppression Analysis

Abstract

The unending demand for high-speed optical communication networks led to the advancement of Dense Wavelength Division Multiplexing (DWDM) systems characterized by enhanced capacity and higher data transmission rates. However, these systems encounter considerable challenges due to propagation impairments, such as chromatic dispersion (CD) and nonlinear phenomena including four-wave mixing (FWM), which compromise signal integrity and limit overall system efficiency. This investigation examines the efficacy of two prominent compensation methodologies, Optical Phase Conjugation (OPC) and Digital Backpropagation (DBP), in alleviating fiber impairments in a 5-channel dual-polarization quadrature phase-shift keying (DP-QPSK) DWDM system on a 50 GHz channel grid. The simulation of the system was conducted utilizing MATLAB, with the input power systematically altered from -2 dBm to 10 dBm, and performance metrics such as Error Vector Magnitude (EVM) and FWM efficiency were scrutinized to assess the efficacy of the techniques. The findings show that Optical Phase Conjugation (OPC) outperforms Digital Back Propagation (DBP) in tackling signal distortions during transmission. OPC significantly reduces unwanted Four-Wave Mixing (FWM) products and achieves better Error Vector Magnitude (EVM) performance. At 6 dBm input power, OPC reduces EVM to 7.2%. DBP only gets it to 10.8%. That is a 33.3% boost in signal clarity for OPC. OPC also cuts FWM products by an extra 1.5 dB across the power range. It handles nonlinear effects better. DBP has complexity and heavy computing needs, which likely makes it less efficient. OPC is more efficient overall. It improves signal quality in multi-channel optical systems. These findings matter a lot. They help build next-generation networks. Those networks will have improved signals. They will handle more data. They will reach farther distances.