Edge Solitons in Nonlinear Photonic Topological Insulators

TL;DR

This paper theoretically demonstrates the existence of unidirectional, self-localized edge solitons in nonlinear photonic topological insulators, revealing new possibilities for optical switching and filtering based on topological phases.

Contribution

It introduces the concept of edge solitons in nonlinear photonic topological insulators and explores their properties in different topological phases, a novel addition to topological photonics.

Findings

Topologically nontrivial phase supports a continuous family of edge solitons.

Topologically trivial phase supports embedded solitons at a single power.

Solitons enable nonlinear filtering and optical switching.

Abstract

We show theoretically that a photonic topological insulator can support edge solitons that are strongly self-localized and propagate unidirectionally along the lattice edge. The photonic topological insulator consists of a Floquet lattice of coupled helical waveguides, in a medium with local Kerr nonlinearity. The soliton behavior is strongly affected by the topological phase of the linear lattice. The topologically nontrivial phase gives a continuous family of solitons, while the topologically trivial phase gives an embedded soliton that occurs at a single power, and arises from a self-induced local nonlinear shift in the inter-site coupling. The solitons can be used for nonlinear switching and logical operations, functionalities that have not yet been explored in topological photonics. We demonstrate using solitons to perform selective filtering via propagation through a narrow channel, and using soliton collisions for optical switching.