Stable Soliton Excitations in Modulational Instability Regime with the Fourth-order Effects

TL;DR

This paper explores stable soliton excitations in a nonlinear fiber influenced by fourth-order effects, revealing their existence in the modulational instability regime and their robustness against perturbations.

Contribution

It demonstrates the existence of stable solitons in the modulational instability regime due to fourth-order effects, a phenomenon not observed with only second- or third-order effects.

Findings

Stable solitons exist in the modulational instability regime with specific profiles.

The solitons are robust against perturbations, confirmed by numerical simulations.

Fourth-order effects are responsible for the formation of these stable solitons.

Abstract

We study the correspondence between modulational instability and types of fundamental nonlinear excitation in a nonlinear fiber with both third-order and fourth-order effects. Some stable soliton excitations are obtained in modulational instability regime, which have not been found in nonlinear fibers with second-order effects and third-order effects. Explicit analysis suggests that the stable soliton existence is related with the modulation stability circle in the modulation instability regime, and they just exist in the modulational instability regime outside of the modulational stability circle. It should be emphasized that the stable soliton just exist with two special profiles on a continuous wave background with certain frequency. The evolution stability of the solitons is tested numerically, which indicate they are robust against perturbations even in modulation instability regime. The further analysis indicates that the solitons in modulational instability regime are caused by the fourth-order effects.