Demonstration of an 8D Modulation Format with Reduced Inter-Channel Nonlinearities in a Polarization Multiplexed Coherent System

TL;DR

This paper introduces an 8D modulation format with polarization management that reduces inter-channel nonlinearities, leading to significant improvements in system margin in both simulation and real-world experiments.

Contribution

It presents a novel 8D modulation format that minimizes inter-channel nonlinearities and demonstrates improved system performance over traditional methods.

Findings

2.33 dB system margin improvement in simulation

1 dB net system margin improvement in experiments

Negligible sensitivity to neighboring channel polarization states

Abstract

We demonstrate a polarization-managed 8-dimensional modulation format that is time domain coded to reduce inter-channel nonlinearity. Simulation results show a 2.33 dB improvement in maximum net system margin (NSM) relative to polarization multiplexed (PM)-BPSK, and a 1.0 dB improvement relative to time interleaved return to zero (RZ)-PM-BPSK, for a five channel fill propagating on 20x80 km spans of 90% compensated ELEAF. In contrast to the other modulations considered, the new 8-dimentional (8D) format has negligible sensitivity to the polarization states of the neighboring channels. Laboratory results from High-density WDM (HD-WDM) propagation experiments on a 5000 km dispersion-managed link show a 1 dB improvement in net system margin relative to PM-BPSK.