Layered Photonic Topological Insulators

TL;DR

This paper introduces layered photonic topological insulators using all-dielectric bilayer photonic crystals, enabling advanced control of light states and promising applications in integrated photonics and information processing.

Contribution

It presents the concept of layered photonic topological insulators based on all-dielectric bilayer structures, incorporating layer pseudospin for enhanced dispersion engineering and novel topological phases.

Findings

Demonstration of layer-polarized and layer-mixed topological insulators.

Observation of layer-direction locking behavior.

High transmission maintained across domain walls despite defects.

Abstract

The recent realization of photonic topological insulators has brought the discovery of fundamentally new states of light and revolutionary applications such as non-reciprocal devices for photonic diodes and robust waveguides for light routing. The spatially distinguished layer pseudospin has attracted attention in two-dimensional electronic materials. Here we report layered photonic topological insulators based on all-dielectric bilayer photonic crystal slabs. The introduction of layer pseudospin offers more dispersion engineering capability, leading to the layer-polarized and layer-mixed photonic topological insulators. Their phase transition is demonstrated with a model Hamiltonian by considering the nonzero interlayer coupling. Layer-direction locking behavior is found in layer-polarized photonic topological insulators. High transmission is preserved in the bilayer domain wall between two layer-mixed photonic topological insulators, even when a large defect is introduced. Layered photonic topological insulators not only offer a route towards the observation of richer nontrivial phases, but also open a way for device applications in integrated photonics and information processing by using the additional layer pseudospin.