Tunability of Spin-Dependent Secondary Topological Interface States Induced in an Optical Complex Superlattice

TL;DR

This paper demonstrates a flexible method to engineer and tune spin-dependent topological interface states in optical superlattices, enabling precise control of localized photonic modes for potential applications.

Contribution

It introduces a novel approach to manipulate secondary topological interface states in complex superlattices using pseudospin and polarization splitting.

Findings

Successful experimental realization of topologically induced interface states

Precise control of spin-dependent modes via superlattice design

Potential for applications in localized light enhancement

Abstract

The past decade has witnessed a booming development of topological photonics, which revolutionizes the methodology for controlling the behavior of light. A gigantic achievement is to engineer robust confined modes localized at interfaces between topologically distinct regions, where the optical context can trigger exotic topological phenomena exclusive to photons. Here, we provide an experimentally flexible approach to engineering topologically induced interface states in the visible regime via a unique design of complex superlattice formed by connecting two component superlattices of distinguished topological phases. Assisted by the intrinsic pseudospin degree due to the splitting between TM and TE polarized modes, we attain a precise manipulation of the spin-dependent topological interface states that can manifest themselves straightforwardly through transmission spectra. More specifically, since these topological localized modes stem from the hybridization of artificial photonic orbitals that are of topological origin as well, they are deemed as a novel topological effect and thus named as the secondary topological interface states. Our work develops an innovative and productive strategy to tune topologically protected localized modes, based on which various applications such as selective local enhancement can be exploited.