Two-component breather solution of the nonlinear wave equation

TL;DR

This paper derives an explicit two-breather molecule solution for a nonlinear wave equation, applicable to various physical contexts, by reducing it to coupled nonlinear Schrödinger equations and analyzing its properties.

Contribution

It introduces a novel analytical two-breather molecule solution for a nonlinear wave equation, connecting it with known solutions in different physics areas.

Findings

The solution describes breathers oscillating with sum and difference frequencies.

It coincides with solutions of well-known equations like Sine-Gordon and Klein-Gordon.

In small amplitude limit, it matches the vector 0π pulse of self-induced transparency.

Abstract

A nonlinear wave equation that describes different nonlinear effects in various fields of research was considered. In two particular cases, this equation was reduced to the Sine-Gordon equation and the Born-Infeld equation. Using the slowly varying envelope approximation and the generalized perturbative reduction method, the nonlinear wave equation was transformed to coupled nonlinear Schrodinger equations for auxiliary functions. An explicit analytical solution of a nonlinear wave equation in the form of a two-breather molecule was obtained. One breather oscillated with the sum, and the other with the difference of frequencies and wave numbers. The obtained solution coincides with the solutions of the two-breather molecule found in a number of well-known equations from different areas of physics. It is shown that in a particular case of the small amplitude waves, a solution in the form of a two-breather molecule for the nonlinear Klein-Gordon equation coincides with the vector 0\pi pulse of the self-induced transparency which is presented under less stringent conditions compared to the same solution of this equation obtained earlier.