Enhanced Regular Perturbation-Based Nonlinearity Compensation Technique for Optical Transmission Systems

O S Sunish Kumar,Abdelkerim Amari,Octavia A Dobre,Ramachandran Venkatesan

doi:10.1109/jphot.2019.2923568

Abstract

The regular perturbation (RP) series used to analytically approximate the solution of the nonlinear Schrodinger equation has a serious energy-divergence problem when truncated to the first order. The enhanced RP (ERP) method can improve the accuracy of the first-order RP approximation by solving the energy divergence problem. In this paper, we propose an ERP-based nonlinearity compensation technique, referred to as ERP-NLC, to compensate for the fiber nonlinearity in a polarization-division multiplexed dispersion unmanaged optical communication system. We also propose a modified perturbation-based NLC (PB-NLC) technique by simple phase-rotation (PR) of the nonlinear coefficient matrix, referred to as the PR-PB-NLC. The PR-PB-NLC can be considered as a by-product of the ERP-NLC technique. We show through numerical simulation that, for a 256 Gb/s single-channel system, the proposed ERP-NLC technique improves the $Q$ -factor performance by $\sim$ 1.2 dB and $\sim$ 0.6 dB when compared to the electronic dispersion compensation (EDC) and the PB-NLC techniques, respectively, at a transmission distance of 2800 km. Also, the result for a 1.28 Tb/s wavelength-division multiplexed five-channel transmission system at the same transmission distance shows that the $Q$ -factor performance of the ERP-NLC technique is improved by $\sim$ 0.6 dB and $\sim$ 0.4 dB when compared to the EDC and the PB-NLC techniques, respectively. The simulation results for the PR-PB-NLC technique for a single- or five-channel transmission system show an improved $Q$ -factor performance when compared to the EDC and PB-NLC techniques. Finally, we show that the proposed performance enhancement comes with a negligible increase in the computational complexity for the ERP-NLC and PR-PB-NLC techniques when compared to the PB-NLC technique.

Highlights

The intra-channel fiber nonlinearity effect is considered a dominant impairment in a dispersion unmanaged optical communication system [1]–[3]
We compare the performance of the enhanced RP (ERP)-nonlinearity compensation (NLC) technique with the single-channel (SC)-Digital back-propagation (DBP), PR-perturbation-based NLC (PB-NLC), PB-NLC, and electronic dispersion compensation (EDC) techniques
It is interesting to note that the PR-PB-NLC technique improves the Q -factor by ∼0.7 dB and ∼0.2 dB when compared to the EDC and PB-NLC techniques, respectively

Summary

Introduction

The intra-channel fiber nonlinearity effect is considered a dominant impairment in a dispersion unmanaged optical communication system [1]–[3]. The first-order RP theory was initially used to model the intra-channel nonlinear distortion effects between short and highly dispersive Gaussian pulses propagating in single-polarization optical fiber links [13]. This technique was later extended to dual-polarization systems and applied as a low-complexity digital NLC in [14]. That is due to the inaccuracy of the first-order RP series approximation for the nonlinear phase-shift To solve this issue, an enhanced RP (ERP) method was proposed in [15], to model the nonlinear signal propagation in the optical fiber. Appendix A provides the detailed derivation of the first-order ERP-based distortion field, and Appendix B considers it’s dual polarization extension

The ERP-Based Approximation of the NLSE

The ERP-NLC Technique

Simulation Setup

Simulation Results and Discussion

Complexity Evaluation

Conclusion