Photonic and plasmonic coupling of metallic nanoantenna supercells: Plasmonic lattices with hybrid cavity modes

Abstract

Using numerical and experimental techniques we study plasmonic and photonic coupling of plasmonic supercells formed in one dimensional arrays (chains) of flat metallic nanoantennas. These supercells support their own collective resonances and are associated with two different types of near field couplings of the nanoantennas. When the incident light is polarized along the long axes the nanoantennas, these cells are formed via plasmonic bonding (bonding supercells). For light polarization along the short axes of the nanoantennas, the supercells are generated via corner edge-mode coupling, generating a collective mode across the one-dimensional arrays of the nanoantennas (cavity supercells). We study plasmonic lattices wherein these supercells act as the units that are periodically repeated along one dimension. By changing the distances between these units (lattice constant), we study the optical responses of such lattices as the nature of interaction between supercells are changed from pure plasmonic (near field) to diffractive (far field) coupling. For lattices with bonding supercells, the former leads to strong suppression of the side modes. In the case of diffractive coupling, our results suggest formation surface lattice resonance via hybridization of resonances of the cavity supercells with Rayleigh anomaly.