Light scattering by a subwavelength plasmonic array: anisotropic model

TL;DR

This paper investigates light transmission through subwavelength plasmonic arrays with anisotropic shapes, revealing sharper resonances in elliptical structures and their sensitivity to refractive index changes, supported by numerical and analytical models.

Contribution

It introduces an anisotropic model for plasmonic arrays, providing analytical expressions and demonstrating the impact of shape and media on resonance behavior.

Findings

Elliptical arrays exhibit sharper plasmonic resonances.

Resonance sensitivity to refractive index variations is significant near total internal reflection.

Analytical models align well with numerical boundary element method results.

Abstract

We calculate the light transmission by a subwavelength plasmonic array using the boundary element method for parallel cylinders with different cross-sections: circular or elliptic with axes ratio 4:1. We demonstrate that the plasmonic resonance is sharper for the case of ellipses with a large horizontal axis. This structure is susceptible to the refractive index variations of media since the high derivative of reflection and transmission coefficients are near the angle of total internal reflection. To obtain an approximate analytical expression, we use the model of a metallic layer. We explore the "sandwich" structure with an anisotropic film between two dielectrics and demonstrate its quantitative agreement with numerical results.