Light transmission by subwavelength annular aperture arrays in metallic films

F.I Baida,D Van Labeke

doi:10.1016/s0030-4018(02)01690-5

Abstract

We study the spectral response of a metallic film with an engraved 2D periodic structure of annular apertures. We show that an enhanced transmission can be obtained and can reach 90%. The variation of the spectral response as a function of the film thickness from 150 nm to a value of 1.8 μm is also studied. We show that a guided mode in the subwavelength coaxial structure is responsible for this large transmission. A wavelength cut-off exists. We study the transmission characteristics on the optical and geometrical parameters of the array (period, coaxial radii, incident polarization and dielectric constants) using a 3D-FDTD algorithm.

Highlights

Since the publication of Ebbesen et al [1], many experimental and theoretical studies were carried out in order to determine the physical origin of the extraordinary enhanced transmission reported in that paper
We have numerically studied the spectral responses of a subwavelength annular aperture arrays exhibiting an extraordinary transmission
We demonstrate the presence of guided mode through the apertures but we are not able to point out the nature of this mode, neither how it is created

Summary

Introduction

Since the publication of Ebbesen et al [1], many experimental and theoretical studies were carried out in order to determine the physical origin of the extraordinary enhanced transmission reported in that paper. Be at the origin of this phenomenon This transmission enhancement is similar to what is observed with frequency selective surface (FSS) components in the spectral region from near-infrared to microwave wavelengths [10,11 and references therein]. Those components are intended for a broad domain of applications such as Fabry–Perot interferometers, filters, couplers for laser cavity output or as polarizers. To increase the transmission of a metal film perforated with subwavelength apertures, it is intuitive to consider a structure that has no cut-off frequency in the desired spectral field. Preliminary results show that such a geometry allows a large increase of the transmission coefficient

Numerical model and simulations

Discussion

Conclusion