Josephson oscillations of edge solitons in a photonic-topological coupler

TL;DR

This paper proposes a photonic topological coupler with Kerr nonlinearity that exhibits Josephson oscillations of edge solitons, highlighting the robustness of soliton pairs with specific phase relations.

Contribution

It introduces a novel photonic coupler design with topological insulator waveguides demonstrating Josephson oscillations of edge solitons and analyzes their stability.

Findings

Single edge solitons decay quickly due to radiation.

Soliton pairs with phase shift π show more robust Josephson oscillations.

Robustness is enhanced by soliton interactions absorbing dispersive waves.

Abstract

We introduce a scheme of a photonic coupler built of two parallel topological-insulator slab waveguides with the intrinsic Kerr nonlinearity, separated by a gap. Josephson oscillations (JO) of a single edge soliton created in one slab, and of a pair of solitons created in two slabs, are considered. The single soliton jumping between the slabs is subject to quick radiative decay. On the other hand, the JO of the copropagating soliton pair may be essentially more robust, as one soliton can absorb dispersive waves emitted by the other. The most robust JO regime is featured by the pair of solitons with phase shift $\pi$ between them.