Topological Floquet interface states in optical fibre loops

TL;DR

This paper reports the experimental observation of topological Floquet interface states in optical fibre loops, demonstrating their robustness to static perturbations and vulnerability to non-stationary ones, advancing understanding of topological photonic systems.

Contribution

First experimental demonstration of coexisting topological Floquet interface states in a (1+1)D optical fibre setup with dynamic control.

Findings

Robustness of topological states against static perturbations

Vulnerability of states to non-stationary perturbations

Implementation of topological transition via phase modulation

Abstract

We experimentally observe a coexisting pair of topological anomalous Floquet interface states in a (1+1)-dimensional Discrete Photon Walk. We explicitly verify the robustness of these states against local static perturbations respecting chiral symmetry of the system, as well as their vulnerability against non-stationary perturbations. The walk is implemented based on pulses propagating in a pair of coupled fibre loops of dissimilar lengths with dynamically variable mutual coupling. The topological interface is created via phase modulation in one of the loops, which allows for an anomalous Floquet topological transition at the interface.