Topological valley crystals in a photonic Su-Schrieffer-Heeger (SSH) variant

TL;DR

This paper introduces a two-dimensional valley photonic crystal based on a deformed SSH model, demonstrating topologically protected valley edge states with robust transmission suitable for THz photonic devices.

Contribution

It proposes a novel valley photonic crystal design using tunable dielectric pillars and reveals vortex valley states with selection rules, advancing valley topological photonics.

Findings

Robust topological edge states maintain transmission at sharp corners.

Design of a rhombus-shaped beam splitter waveguide for valley-chirality selection.

Numerical validation of valley-protected transport in the proposed structure.

Abstract

Progress on two-dimensional materials has shown that valleys, as energy extrema in a hexagonal first Brillouin zone, provides a new degree of freedom for information manipulation. Then valley Hall topological insulators supporting such-polarized edge states on boundaries were set up accordingly. In this paper, a two-dimensional valley photonic crystal composed of six tunable dielectric triangular pillars in unit cells is proposed in the photonic sense of a deformed Su-Schrieffer-Heeger (SSH) model. We reveal the vortex nature of valley states and establish the selection rules for valley polarized states. Based on the valley topology, a rhombus-shaped beam splitter waveguide is designed to verify the valley-chirality selection above. Our numerical results entail that this topologically protected edge states still maintain robust transmission at sharp corners, henceforth providing a feasible idea for valley photonic devices in THz regime.