Nanogroove array on thin metallic film as planar lens with tunable focusing

TL;DR

This paper demonstrates that nanogroove arrays on thin gold films can function as tunable planar lenses, with focus and focal length adjustable by wavelength and groove design, based on numerical simulations.

Contribution

It introduces a novel design of metallic planar lenses using nanogroove arrays with tunable focusing properties demonstrated through numerical analysis.

Findings

Optimal groove width variation achieves near-field focusing

Focal length significantly depends on incident light wavelength

Numerical results validate the tunability of the lens design

Abstract

Numerical results for the distributions of light transmitted through metallic planar lenses composed of symmetric nanogroove arrays on the surfaces of a gold film are presented and explained. Both the near- and far-field distributions of the intensity of light transmitted are calculated by using a Green's function formalism. Results for an optimal transverse focus based on a quadratic variation of groove width are obtained. Meanwhile, a significant dependence of the focal length on the wavelength of light incident from the air side through the gold film into a dielectric substrate is found for this detector configuration.