Unidirectional transmission based on polarization conversion and excitation of magnetic or surface polaritons

Xiaohu Wu,Ceji Fu

doi:10.1063/1.4994686

Abstract

We propose in this work combing a uniaxial crystal slab with a one-dimensional grating to realize unidirectional transmission (UDT). The physical mechanism for the UDT is attributed to polarization conversion with uniaxial crystal slab and excitation of magnetic polaritons (MPs) or surface plasmon polaritons (SPPs) in the grating region. Numerical simulations were performed by taking hexagonal boron nitride as the uniaxial crystal. The results reveal that UDT can be achieved for both TE and TM waves in the mid-infrared and the optical regions if the grating material is respectively selected as silicon carbide (SiC) and silver (Ag) with properly chosen values of the structure’s geometric parameters. This work may provide important guidelines for design of novel unidirectional transmission devices.

Highlights

During the past several years researches have been extensively conducted to realize unidirectional transmission with different structures and materials
It has been shown that Unidirectional transmission (UDT) can be achieved using specially designed photonic crystals due to the existence of topological edge state,[1] Dirac point[2] and Dirac cone[3] wherein, and by using gratings owing to the excitation of surface plasmon polaritons (SPPs)[5] and the resonance of guided modes.[10]
Realization of UDT have been demonstrated with metamaterials (MMs),[11,12,13,14,15,16,17,18,19] bianisotropic metasurfaces,[20] magneto-optical materials[21,22] and chiral structures[23] based on polarization conversion between the transverse magnetic (TM) wave and the transverse electric (TE) wave

Summary

Introduction

During the past several years researches have been extensively conducted to realize unidirectional transmission with different structures and materials. We propose an alternative approach to fulfill polarization conversion with a uniaxial crystal plate, with which a grating is combined to realize UDT based on the excitation of magnetic polaritons (MPs) or SPPs. In our case, neither the MMs nor the magneto-optical materials are needed.

Results

Conclusion