Exactly solvable model for nonlinear pulse propagation in optical fibers

TL;DR

This paper introduces an integrable generalization of the nonlinear Schrödinger equation to model nonlinear pulse propagation in optical fibers, linking it to the derivative NLS hierarchy and analyzing traveling-wave solutions.

Contribution

It presents a new integrable model for nonlinear pulse propagation in fibers, connecting higher-order effects to the derivative NLS hierarchy and exploring its solutions.

Findings

The generalized NLS equation models higher-order nonlinear effects in optical fibers.

It is equivalent to a member of the derivative NLS hierarchy.

Traveling-wave solutions are analyzed within this framework.

Abstract

The nonlinear Schr\"odinger (NLS) equation is a fundamental model for the nonlinear propagation of light pulses in optical fibers. We consider an integrable generalization of the NLS equation which was first derived by means of bi-Hamiltonian methods in [A. S. Fokas, {\it Phys. D} {\bf 87} (1995), 145--150]. The purpose of the present paper is threefold: (a) We show how this generalized NLS equation arises as a model for nonlinear pulse propagation in monomode optical fibers when certain higher-order nonlinear effects are taken into account; (b) We show that the equation is equivalent, up to a simple change of variables, to the first negative member of the integrable hierarchy associated with the derivative nonlinear Schr\"odinger equation; (c) We analyze traveling-wave solutions.