Unidirectional light transport in dynamically modulated waveguides

TL;DR

This paper demonstrates how unidirectional light transport can be achieved in one-dimensional dynamically modulated waveguides, offering a simpler alternative to two-dimensional topological insulators with potential for robust photonic applications.

Contribution

It introduces the concept of unidirectional Floquet bands in 1D systems, contrasting with the 2D requirement in topological insulators, and shows practical implementation methods.

Findings

Unidirectional Floquet bands can arise in 1D modulated systems.

Protection against disorder is demonstrated, with a novel nature compared to 2D topological insulators.

Implementation feasible with realistic experimental parameters.

Abstract

One-way edge states at the surface of photonic topological insulators are of significant interest for communications, nonlinear and quantum optics. Moreover, when reciprocity is broken in a photonic topological insulator, these states provide protection against disorder, which is of particular importance for slow light applications. Achieving such a one-way edge state, however, requires the construction of a two-dimensional structure. Here, we show how unidiriectional Floquet bands can arise in purely one-dimensional, adiabatically-modulated dynamic systems, in contrasts with the higher dimensionality needed in topological insulators. We also show that, using realistic experimental parameters, the concept can be implemented using both a coupled-resonator optical waveguide and a photonic crystal waveguide. Furthermore, we illustrate the associated protection against disorder, and find it to be of a novel nature when compared to Floquet topological insulators.