Symmetrical and anti-symmetrical topological edge states based on two-dimensional magneto-optical photonic crystals

Hua-Shan Lai,Yan-Feng Chen,Cheng He,Bo He,Hao Chen

doi:10.1063/5.0011727

Abstract

We report our design of a topological waveguide at the boundary of two adjacent magneto-optical photonic crystals with opposite magnetic biases which can simultaneously support symmetrical and anti-symmetrical topological edge states. In this non-reciprocal topological photonic model, the symmetrical and anti-symmetrical topological edge states possess the same direction of backscattering-immune chiral energy propagation. However, their directions of phase propagation are opposite, i.e., forward phase propagation for the symmetrical state while backward for the anti-symmetrical one. Using a finite-size structure, we can selectively couple one topological edge state to free space via oblique incidence to realize one-way transmission and reflection in a compact configuration. Furthermore, we design an all-photonic tunable splitter by hybridizing these two topological states. Based on manipulating the phase propagation of topological edge states, our work may offer promising applications in tunable topological photonics and extend the scope of topological photonics.

Highlights

Topological phases of matter have attracted intense attention in past decades due to the robustness in energy and information transportation
Symmetrical and anti-symmetrical topological edge states based on two-dimensional magneto-optical photonic crystals
One well-known topological case is the quantum Hall effect (QHE) discovered in 1980.1 The quantized Hall conductance originated from the nontrivial topology of band structures with periodical structures, e.g., the Chern number which can characterize the global properties of materials

Summary

Introduction

Topological phases of matter have attracted intense attention in past decades due to the robustness in energy and information transportation. Symmetrical and anti-symmetrical topological edge states based on two-dimensional magneto-optical photonic crystals Engineering the phase propagation in topological photonic scitation.org/journal/adv metamaterials may bring some useful functional photonic devices, such as negative refractions33 and perfect lenses beyond the diffraction limit.34,35 On the other hand, topological edge states are usually located at the boundary between two topologically distinct materials.

Results

Conclusion