Coupled surface plasmons in a thin free-standing metal film with both the interfaces periodically corrugated are studied. Infinite Rayleigh expansions in terms of the spatial harmonics with proper boundary conditions are used to obtain the infinite hierarchy of coupled amplitude equations. The truncated system of equations is numerically solved to explain the experimental results of Inagaki et al. [Phys. Rev. B 32, 6238 (1985)]. The theoretical investigation goes beyond the range of the parameters used in the experiment and we reveal the nonperturbative character of the peak intensities as a function of the corrugation amplitude.

• Received 23 April 1987

DOI:https://doi.org/10.1103/PhysRevB.36.6331