Topological solitons in coupled Su-Schrieffer-Heeger waveguide arrays

TL;DR

This paper explores how coupling multiple SSH waveguide arrays creates diverse topological edge states and solitons, revealing new stable topological structures influenced by array coupling and nonlinearity.

Contribution

It demonstrates the emergence of multiple topological edge states and solitons in coupled SSH waveguide arrays, highlighting the impact of array coupling and nonlinearity on topological phenomena.

Findings

Multiple topological edge states depend on the number of arrays in topologically nontrivial phases.

Coupling induces a variety of stable topological edge solitons with different symmetries.

Nonlinearity enables the formation of families of multipole topological edge solitons.

Abstract

We investigate the formation of multipole topological solitons at the edges of two and three coupled parallel Su-Schrieffer-Heeger (SSH) waveguide arrays. We show that independent variations of waveguide spacing in the unit cells (dimers) in coupled waveguide arrays result in the emergence at their edges of several topological edge states with different internal symmetry. The number of emerging edge states is determined by how many arrays are in topologically nontrivial phase. In the presence of nonlinearity, such edge states give rise to families of multipole topological edge solitons with distinct stability properties. Our results illustrate that coupling between quasi-one-dimensional topological structures substantially enriches the variety of stable topological edge solitons existing in them.