Terahertz Plasmonic Transport in Topological Valley Metal-slabs

TL;DR

This paper introduces ultrathin metal-slab Kagome photonic insulators that enable robust, topologically protected terahertz waveguiding with potential for compact, integrated photonic circuits.

Contribution

It proposes a novel topological THz waveguide design using Kagome lattices with symmetry-breaking to achieve robust plasmonic transport.

Findings

Demonstrated topological phase transitions via lattice rotation.

Verified robustness of THz waveguiding through sharp corners.

Showed positive/negative refraction of valley edge states.

Abstract

Topological photonic devices have attracted great attentions in terahertz (THz) and optical regimes due to their robust protected transport properties. However, it remains challenging in miniaturization of the devices to get superior performance for photonic integrated circuits in optical networks. In this paper, Kagome photonic insulators constructed with ultrathin metal-slab on Polyimide substrate are proposed for THz waveguiding. Theoretical analysis and numerical simulation demonstrate that $C_{3v}$ symmetry can be broken by global rotation $\theta$ of the air holes in metallic Kagome lattice, providing topological phase transitions. The propagation of THz waves through Z-shaped domain walls with multiple sharp corners verifies the robustness of plasmonic transport. The positive/negative refraction of topological valley edge state from Zigzag interface into background space is illustrated. These results present a novel approach to manipulate THz waves and facilitate development of photonic integrated circuits with high compactness and robustness.