Spectral and angular distribution of Rayleigh scattering from plasmon-coupled nanohole chains

We experimentally investigate the optical properties of nanohole chains in 20 nm gold films by measuring the far-field radiation patterns and scattering spectra using both white light and single-frequency laser excitations. We observe intensity enhancement in the frequency spectrum originating from resonantly coupled nanohole excitations via thin film surface plasmon polaritons. However, the angular distribution of the far-field pattern is identical to that of a chain of coherently radiating point dipoles both on and off the resonance frequency. We highlight a potential of the k-space imaging technique for studying far-field properties of ordered nanoscale structures.