Optical field enhancement in composite plasmonic nanostruc- tures: gold dots with graphene and dye R6G

We present composite plasmonic nanostructures designed to achieve cascaded enhancement of electromagnetic fields at optical frequencies. Our structures are made with the help of electron beam lithography and comprise a set of self-similar metallic nano-discs placed one above another. The optical properties of reproducible arrays of these structures are studied using scanning confocal Raman spectroscopy. We observe significant (up to 1000 times) enhancements of resonant Raman scattering from a graphene layer generated by near-fields of a plasmonic nanoarray. This enhancement is quantitatively explained by the electromagnetic mechanism.