Multiple intersection properties of optical resonance modes in metallic metamaterials

Yasunori Tokuda,Yuki Yamaguchi,Koichiro Sakaguchi,Keisuke Takano

doi:10.1063/1.4978616

Yasunori Tokuda, Yuki Yamaguchi + Show 2 more

Open Access

https://doi.org/10.1063/1.4978616

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Journal: AIP Advances	Publication Date: Mar 1, 2017
Citations: 4	License type: CC BY 4.0

Affiliation: Okayama Prefectural University, Osaka University

Abstract

Unusual behavior of Fabry-Perot-like waveguide resonance modes is presented for a quasi-dielectric metamaterial that consists of two metallic sub-wavelength cut-through slit-array slabs separated by an air-gap region. Simulations based on the finite-difference time-domain method were conducted. The unique optical properties were interpreted in terms of multiple intersection of the resonance modes. Depending on the intersection conditions of the optical modes, furthermore, a variety of crossing characteristics, i.e., fade-out crossing with/without an isolated loop, anticrossing with/without intensity reduction, and anticrossing with/without frequency repulsion, were identified for the air-gap dependence of the transmission spectra. These findings, which were obtained by careful observation of the properties of this type of metamaterial, present a novel and interesting aspect of the behavior of the optical resonance modes.

Highlights

Optical transmission spectra of metallic slabs that are cut through with sub-wavelength periodic slit patterns are characterized by Fabry-Perot-like waveguide resonance when the incident wavelengths are longer than the slit intervals.[1,2,3,4,5,6] Even though the bodies of the structures are made of metal, almost 100% transmission is achieved at the resonance frequencies; this so-called extraordinary optical transmission has received considerable attention in the highly active research area of metamaterials.[7]
We have formulated the effective refractive index of the air-gap layer that is sandwiched by the slit-array slabs,[19] and demonstrated that most of the intersections of the optical resonance modes can be regarded fundamentally as anticrossings, in which the mode repulsions are recognized only when the effective refractive indices in the air-gap regions are considerably increased.[20]
We present more unusual behavior of the optical resonance modes observed in the metamaterial system, and consider the physical mechanism, using simulations based on the finitedifference time-domain (FDTD) method

Summary

Introduction

Optical transmission spectra of metallic slabs that are cut through with sub-wavelength periodic slit patterns are characterized by Fabry-Perot-like waveguide resonance when the incident wavelengths are longer than the slit intervals.[1,2,3,4,5,6] Even though the bodies of the structures are made of metal, almost 100% transmission is achieved at the resonance frequencies; this so-called extraordinary optical transmission has received considerable attention in the highly active research area of metamaterials.[7]. Multiple intersection properties of optical resonance modes in metallic metamaterials

Results

Conclusion