Plasmonic Crystals with Conical Perforations as Multipurpose Optical Elements

Abstract

Plasmonic crystals exhibit excellent waveguiding and extreme light localizing properties. However, if additionally perforated, their structure assumes vastly enhanced functionality and becomes the basis for e.g. double negative refractive index metamaterials and superabsorbers. In this work we consider 1D plasmonic crystal consisting of alternating metallic and dielectric layers perforated by an array of conical holes tapering off as they penetrate the multilayer. We utilized the finite element method (Comsol multiphysics®) to calculate the response of our proposed structures - electromagnetic field intensity and frequency dispersion of scattering parameters. Utilizing at the same time a multilayer and perforations with a varying cross section simultaneously broadens the useful spectrum and allows for additional plasmonic modes. In addition to an enhanced absorption associated with the plasmonic modes, the functionality of the structure is further increased by allowing spectral selection of dielectric layers with strong light localization. The proposed structure can be used for a multitude of practical applications. They include (but are not limited to) an alternative approach to superabsorber design, the enhancement of the performance of multianalyte biochemical sensors, photo detectors, solar cells and photocatalysts, as well as optical switching.