Angular resolved transmission spectra of corrugated metallic films and gratings: Localized and surface plasmons

We report on the optical properties of silver films and nanowires grown on laser-patterned polyethyleneterephthalate (PET) foils. Polymer substrates with Laser Induced Periodic Surface Structures (LIPSS) were used as templates for vacuum evaporation of silver. Metal deposition under normal and grazing angle of incidence resulted in corrugated silver layers and nanowire gratings, respectively. The samples were studied with polarization resolved transmission spectroscopy. Angle dependent spectra were recorded by tilting the sample stepwise from 0 to 50°, with the plane of incidence parallel or perpendicular to the nanowires. The energy of the localized plasmon excited on the nanowire grating by light polarized perpendicular to the nanowire axis depends mostly on the dimension of the nanowires (width). On the other hand, transmission spectra of the thin corrugated metal layer show a strong angular dependence, owing to the propagating nature of the corresponding surface and interface plasmons.