Quasi-analytic study of scattering from optical plasmonic patch antennas

We present an analytical treatment of the optical scattering from film-coupled nanocubes. Film-coupled nanoparticles are a convenient platform for the demonstration of a variety of fundamental plasmonic phenomena, including nonlocality and field enhancement, and can also serve as the basis for controlled reflectance surfaces. The nanocube geometry is particularly amenable to analysis, since the cubes behave in large part as plasmon resonant patch antennas, allowing the well-known patch antenna equations to be applied with some modifications. In particular, we make use of the plasmon dispersion relation to avoid direct calculation of the effective inductance per unit length—which would include kinetic inductance contributions—instead calculating the effective waveguide mode index to incorporate plasmonic contributions. We compare the analytically derived field enhancement and spectral characteristics of the film-coupled nanoparticles with those obtained from full-wave finite-element simulations.