Families of solitons in Bragg supergratings

TL;DR

This paper investigates the existence and properties of gap solitons in a fiber Bragg grating with superimposed periodic modulations, revealing new bandgap structures and soliton bifurcations through analytical and computational methods.

Contribution

It introduces a comprehensive analysis of gap solitons in supergratings, including asymmetric and bound states, expanding understanding of their bifurcations and spectral properties.

Findings

Supergratings create new bandgaps filled with gap solitons.

Existence of asymmetric and bound state solitons in supergratings.

Bifurcation analysis reveals complex soliton dynamics.

Abstract

We study fundamental optical gap solitons in the model of a fiber Bragg grating (BG), which is subjected to a periodic modulation of the local reflectivity, giving rise to a supergrating. In addition, the local refractive index is also periodically modulated with the same period. It is known that the supergrating opens an infinite system of new bandgaps in the BG's spectrum. We use a combination of analytical and computational methods to show that each emerging bandgap is filled with gap solitons (GSs), including asymmetric ones and bound states of the GSs. In particular, bifurcations of the GSs created by the supergrating are studied in terms of a geometric analysis.