An analytical approach to light scattering from small cubic and rectangular cuboidal nanoantennas

Abstract

At optical frequencies metals behave as an electron plasma and conventional antenna designs need modifications when transferred to this regime. In contrast to antenna theory and to the effective wavelength picture, the position and width of the dipolar resonance of a rectangular cuboidal plasmonic nanoantenna scales nonlinearly with its length, width and height, as shown in this paper directly by analytical formulae. Moreover we show that the quality factor calculated for different sizes varies significantly with size, in contrast to the quasi-static approximation which predicts invariance. We present analytical expressions that provide a tool for direct and precise calculation of the dipolar plasmon resonance which can be applied to the antenna design process. These expressions enable both physical insight and the quick exploration of a wide range of parameters to tailor the plasmon resonance response or scattering by nanoparticles, for either metals or dielectrics, for numerous promising applications in optical sensor, photovoltaic and light emitting device design.