Optical transmission through a very small nanoaperture decorated with concentric gratings on the apex of a metallic micropyramid can guide the beam path after transmission. A micro-pyramidal probe with periodic grooves acts as an antenna in terms of beam radiation as well as a lens in terms of beam focus. We optically resolve that the transmitted beam is splitted to the corresponding pyramid surfaces guided by gratings. By using the pseudo-Kretschmann configuration and grating surface plasmon polariton coupling, we can explain that SPPs propagating along a pyramidal surface modulated with a grating couple to light and thus radiate. The work may lead to more sensitive probes of the optical properties of nanostructures.
Project end date: 02/06/12