Tunable and polarization insensitive plasmon resonance gratings based on spheroidal nanoparticles

Abstract

The optical properties of arrays of plasmonic nanoparticles (NPs) been the subject of extensive research in recent years. Plasmonic NPs with dimensions much smaller than the incident wavelength display a resonant behavior where the electromagnetic (EM) fields are strongly enhanced and highly confined to the surface of the NP. This property of plasmonic NPs is of great interest in numerous applications. Most theoretical studies have utilized spherical NPs. This is due to the fact that scattering behavior of spheres can be studied analytically. In a recent paper, it was shown that by using spheroidal NPs, it is possible to tune the resonance frequency. However, the response of such structures is highly polarization dependent. In this paper, we propose how it is possible to overcome this polarization dependence using a new unit cell geometry.