Giant enhancement of elastic surface plasmon-polariton scattering.

Here we report the first (as far as we know) experimental observation of extremely high enhancement factor due to elastic surface plasmon-polariton scattering by surface singularities.We have observed strong diffraction of surface plasmon-polaritons by shallow diffraction grating while its illumination by evanescent or volume waves do not shows any traces of diffraction structure in space distribution of scattered light.