Parallel Digital Backpropagation in Fiber Optics Considering Four-Wave Mixing Terms

Digital backpropagation (DBP) is the most effective fiber optic compensation technique. While DBP can increase the achievable data rate, its high computational complexity prevents its use in real-time applications. Parallelization is one of the most promising techniques to allow real-time DBP. Existing parallel DBP (PDBP) are based on coupled nonlinear Schrodinger equation (NLSE), which only considers cross-phase modulation and discards the rest of the inter-channel impairments. Therefore, these methods lose their performance in today's wavelength-division multiplexing systems. We fill this gap by proposing a PDBP capable of working with regular NLSE and compensating for all fiber impairments, including four-wave mixing. We analytically derive the compensation equations for the parallel scheme and handle them efficiently to reduce the complexity. Our simulations show a significant improvement in the sense of optimal launched power, achievable data rate, and system reach over existing DBPs with comparable complexity.