Photoacoustic study of plasmon-resonance absorption in a bigrating

Plasmon-resonance absorption of 633-nm photons in a silver-coated bigrating (crossed grating) was measured by a photoacoustic method. The bigrating studied had two sets of corrugations perpendicular to each other, which were made by the holographic method. The corrugation amplitude h = 48 nm and the groove spacing d = 2186 nm were the same for both corrugations. The results obtained as a function of the groove orientation relative to the plane of photon incidence were found to be consistent with predictions of a perturbation theory. For the case in which two plasmon waves were generated simultaneously in directions symmetric with respect to the plane of incidence, a significant redistribution of the absorption intensity was found to occur between the incident p- and s-polarized light