Implementation of Backward Surface Waves by Multilayered Metal-Dielectric Metamaterials Partnering with Conventional Dielectric Media

Zhiyuan Zhou,Yuxiao Wang,Jian Xin,Xueru Zhang,Yinglin Song

doi:10.3390/app8091420

Abstract

It has been reported that backward surface waves of Tamm state can be supported by a multilayered metal–dielectric metamaterial with different partner materials, such as left-handed metamaterial or dissimilar metallic–dielectric metamaterial. In this paper, the transfer-matrix method is employed to reveal that transverse-magnetic (TM)-polarized backward surface waves can be realized by a multilayered metal–dielectric metamaterial in contact with a conventional homogenous dielectric medium. Owing to the strong optical nonlocality, the existence of such backward surface waves is proved to be dependent on the order of the metallic/dielectric layers. The relevant anomalous dispersion relations can also be dramatically engineered by varying the unit-cell thickness and the filling factor. Additionally, the distribution of the energy flow is presented to further unfold the physical mechanism of the backward surface waves. Finally, a numerical simulation of backward surface wave excited by a TM-polarized Gaussian beam based on a prism-coupled configuration is displayed.

Highlights

Optical surface waves (SWs), which are a special class of electromagnetic waves propagating along the interface of two dissimilar materials with fields decaying exponentially away from the interface, have been extensively studied in the last century
SWs can be realized when the partner media have opposite signs of dielectric functions [1], which leads to surface plasmon polaritons (SPPs) [9], or at least one of the partner media is anisotropic, which leads to Dyakonov SWs [10,11], or one of the partner media is periodically inhomogeneous in the direction normal to the interface, which leads to Tamm SWs [12,13]
We demonstrate that transverse-magnetic (TM)-polarized backward SWs can be implemented by a conventional homogenous dielectric medium in contact with an multilayered metal–dielectric metamaterials (MMDMs)

Summary

Introduction

Optical surface waves (SWs), which are a special class of electromagnetic waves propagating along the interface of two dissimilar materials with fields decaying exponentially away from the interface, have been extensively studied in the last century. Electromagnetic analogue of Tamm state localized at the interface of different partner media has been extensively researched, including two dissimilar photonic crystals [26], an MMDM in contact with a left-handed metamaterial [27], two dissimilar MMDMs [28], or a hyperbolic metamaterial heterostructure consisting of stacked graphene sheets separated by dielectric layers [29]. It has been reported that both the thickness [35] and the order [24] of the metallic and dielectric layers have significant influence on the optical nonlocality of MMDMs due to the excitation of SPPs, resulting in the dispersions and diffraction properties of SWs supported by MMDMs that may severely deviate from the results acquired by the EMA method. A simulation of a forward SW is presented for comparison

Theoretical Modal and Transfer-Matrix Method for TM-polarized Surface States

Numerical of Backward

Backward

Forward

Findings

Conclusions