Grating-induced cross coupling of surface polaritons

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Abstract
We present results of calculations of the reflectivity of a dielectric diffraction grating with a thin metal overlayer. In this geometry, surface polaritons existing on opposite sides of the corrugated metal overlayer can couple to each other via a grating reciprocal lattice vector. We investigate this coupling in the geometry used in recent experiments by Brueck, Diaduik, Jones, and Lenth. We find good agreement between our theory and their experimental results, and we conclude that the cross coupling of surface polaritons is so weak in this geometry that it is experimentally unobservable. We also discuss calculations of the reflectivity of the free-standing films studied recently by Inagaki, Motosuga, Arakawa, and Goudonnet.