Resonant coupling of surface and bulk plasmon polaritons in metallic nanostructures

Sub-nanometer transition layers that arise at interfaces between a metal and a dielectric sufficiently modify wave-guiding properties of metallic nanostructures. Through nonuniformities occurring inside the transition layers, the plasmon polariton modes maintained by a metal/dielectric interface couple to each other and change energy confinement in the nanostructure. In order to investigate this coupling, a continuous transition arising at a flat interface between gold and silicon dioxide is studied and analyzed with respect to the eigen modes supported by such a waveguide structure.