Enhanced spontaneous parametric down-conversion in a metal-dielectric interface

Spontaneous parametric down-conversion in a metal-dielectric interface in the case of oblique laser excitation is considered. In this case it is possible to generate pairs of surface plasmon polaritons with high efficiency, if the angle of excitation corresponds to the Kretschmann configuration for generated plasmons. The efficiency can be additionally increased/enhanced if to use metal-dielectric interfaces with long-range surface plasmon polaritons and/or a properly nanostructured metallic film, allowing one to directly excite surface plasmon polaritons and to fulfill their phase matching condition with generated surface plasmon polaritons.