A Unified Design Framework for Single-Channel Dispersion-Managed Terrestrial Systems

Abstract

Abstract-This paper provides a unified framework to the design, performance optimization, and accurate numerical simulation of periodic, dispersion-managed (DM) single-channel long-haul optical transmission systems for nonsoliton on-off keying (OOK) modulation. The focus is on DM terrestrial systems, with identical spans composed of a long transmission fiber compensated at the span end by a linear dispersion compensating module, with pre-and postcompensation fibers at the beginning and end of the link. The framework is based on the dispersion-managed nonlinear Schrödinger equation (DM-NLSE). First, expressions of the DM-NLSE kernel are provided both in the frequency and the time domain, and a novel map strength parameter, appropriate for terrestrial systems, is introduced. It is then shown that the DM-NLSE contains all the basic information needed for system design, as summarized by three parameters: i) nonlinear phase, ii) in-line dispersion, and iii) map strength. Through a large-signal perturbative analysis of the DM-NLSE, the well-known linear relationship between the in-line dispersion and the optimal precompensation is derived, along with the large-signal step response of the DM link, from which the ghost pulses energy growth and a first estimation of the link memory are derived. The DM-NLSE is then linearized around the average signal field to get the amplitude/phase small-signal system matrix of the overall DM link, including pre-and postcompensation. By a singular-value decomposition of the small-signal DM link matrix, a novel expression of the memory of the optimized DM link is finally provided. Knowledge of such a memory is mandatory to run accurate numerical simulations and laboratory measurements with a sufficiently long pseudorandom bit sequence to avoid patterning effects.Index Terms-Dispersion-managed nonlinear Schrödinger equation, optical fiber memory, perturbation methods, pseudorandom binary sequence (PRBS) length, small-signal analysis.

Nonlinear signal–noise interactions in dispersion-managed links with various modulation formats

“…As in Section 2, pre-compensation was selected according to the single-channel noiselessoptimized straight-line rule (SLR) [2,33]:…”

“…Single-channel noiseless-optimized net residual dispersion D tot ¼ D pre þ ND in þ D post was selected according to the rule [2]:…”

“…-Only one run is needed in single-channel propagation when using a sufficiently long De Brujin sequence that captures all possible inter-symbol interference (ISI) patterns within the memory length of the DM line [2,3]; -Several runs are needed in WDM propagation in order to test different time and phase offsets among the channels, all modulated with different De Brujin sequences.…”

Cross-Phase Modulation Induced by OOK Channels on Higher-Rate DQPSK and Coherent QPSK Channels

“…The transmission fiber was a non-zero dispersion shifted fiber (NZDSF) with dispersion . The dispersion of the pre-compensating fiber was selected according to the "straight line rule" (SLR) [29], [30] as: , where three different values of the residual in-line dispersion per span were used:…”

“…5 for the case of both NZDSF and SMF transmission fiber, using either 50 GHz or 100 GHz channel spacing. The launched average power for all channels was in each case, corresponding to a cumulated nonlinear phase [30]. SSFM simulations in this case did not include SPM.…”