Anti-chiral edge states based on photonic Floquet lattices

TL;DR

This paper introduces a photonic Floquet lattice design that supports anti-chiral edge states with controllable transmission properties, expanding the understanding of topological photonics and enabling new optical device applications.

Contribution

It proposes a novel waveguide structure combining two honeycomb Floquet lattices with opposite rotations to realize anti-chiral edge states with tunable robustness and transmission speed.

Findings

Anti-chiral edge states have the same transmission direction on parallel edges.

The band gap width decreases with increasing phase difference.

Transmission speed is controllable via phase difference.

Abstract

Photonic Floquet lattices provide an excellent platform for manipulating different topologically protect-ed edge states. However, anti-chiral edge states have not been discussed much in Floquet lattices. Here, we propose a waveguide structure by combining two honeycomb Floquet photonic lattices with oppo-site rotation directions. In this structure, we find that the anti-chiral edge states have the same trans-mission direction on two parallel body edges. With an increasing modulation phase difference between the two sublattices in one direction, the width of the band gap becomes smaller and the robustness of the edge states becomes weaker. Interestingly, the transmission speed is also controlled by the phase difference. In addition to their relevance for the topological properties of the Floquet lattice system, these results may be applied to multi-channel optical switches, optical functional devices, and in other fields.