Coupling between a sub-wavelength optical cavity and a plasmonic nanostructure probed by SERS

We report on the utilization of optical sub-wavelength quasi Fabry-Perot cavity coupled with the Raman microscopy to study the interaction between the localized surface plasmon resonance of gold nanoparticles and the surface plasmon resonance of a gold film. We show an enhancement of the Fabry-Perot oscillations when the distance between nanoparticle and gold film decrease.