Floquet defect solitons

TL;DR

This paper investigates Floquet defect solitons in a nonlinear waveguide array with a line defect, revealing how linear defect modes bifurcate into bright or dark solitons under nonlinearity, with numerical analysis of their dynamics and stability.

Contribution

It introduces a novel model of Floquet defect solitons in a modulated waveguide lattice, analyzing their bifurcation, types, and stability.

Findings

Defect modes correspond to tilted layers in the lattice.

Nonlinear bifurcation leads to bright or dark solitons.

Numerical simulations confirm soliton stability and dynamics.

Abstract

We consider an array of straight nonlinear waveguides constituting a two-dimensional square lattice, with a few central layers tilted with respect to the rest of the structure. It is shown that such configuration represents a line defect, in the lattice plane, which is periodically modulated along the propagation direction. In the linear limit, such a system sustains line defect modes, whose number coincides with the number of tilted layers. In the presence of nonlinearity the branches of defect solitons propagating along the defect line bifurcate from each of the linear defect modes. Depending on the effective dispersion induced by the Floquet spectrum of the underline system the bifurcating solitons can be either bright or dark. Dynamics and stability of such solitons are studied numerically.