Comparison of Ag and Si nanoparticle arrays: mimicking subwavelength plasmonic field concentrations with dielectric components

Abstract

We present a comparative theoretical study of the optical response of metallic Ag and dielectric Si sphere arrays on top of reflecting substrates. The interaction of particle modes with guided modes of the substrate leads to a rich optical spectrum. We design structures that sustain highly concentrated electromagnetic fields around periodic arrays of Si nanoparticles through the coupling of incident light to waveguide modes of a dielectric spacer. We discuss the origin of the different modes responsible for the reflectivity spectra of particle arrays and propose that all dielectric structures can support strong field enhancement which is similar to nanostructured metallic surfaces.