Topological multiband photonic superlattices

TL;DR

This paper explores the topological properties of one-dimensional photonic superlattices with multiple elements per unit cell, revealing tunable edge and interface states and potential applications in mode multiplexing.

Contribution

It extends the understanding of topological states in photonic lattices to superlattices with arbitrary unit cell sizes, demonstrating tunability and stability of multiple topological states.

Findings

Tunable number of topologically protected edge and interface states.

Stable propagation and interference of multiple topological states.

Potential for topologically protected mode-division multiplexing.

Abstract

A one-dimensional discrete lattice of dimers is known to possess topologically protected edge states when interdimer coupling is stronger than intradimer coupling. Here, we address richer topological properties of photonic superlattices having arbitrary number of elements in each unit cell. It is shown that the superlattice provides tunable number of topologically protected edge and interface states depending on certain restrictions on intra- and intercell couplings maintaining inversion symmetry of the lattice. Simultaneous and stable propagation of multiple topological interface states, their interference pattern, and stable oscillation are reported. The superlattice configuration can be relevant for topologically protected mode-division multiplexing through a narrow route in photonic devices.