Coupling of surface plasma oscillations in thin periodically corrugated silver films

We investigated surface plasma oscillations (SPO's) in a layer system of thin dielectric films with a periodically corrugated surface coated by a silver film. SPO's at both surfaces of the silver film could be excited by light. We observed coupling of the two SPO's through the thin film via the periodicity of the surface and as a consequence a discontinuity in the dispersion relations of the SPO.