Self-assembled hybrid photonic/plasmonic nano composites for sensing applications

Photonic cavities with high quality factor (up to Q>3000) sustainning lasing action with threshold as low a ~35 kW/cm2 can be self-assembled using nanotechnology approaches without the need for lattice matching substrates. On the other hand, plasmonic resonances, originating in localised surface plasmons (LSP), can efficiently store optical energy in the form of electron oscillations at the interface of metallic clusters and dielectrics; they are, in fact, the main contributors of the large enhancement effects observed in Surface Enhanced Raman Scattering (SERS). In this contribution we present our work on hybrid photonic-plasmonic nanostructures for the development of SERS substrates enabling the identification of ultra-small traces of chemicals including food contaminants. The experimentally determined enhancement factors are compared with numerical simulations using a FDTD algorithm. We discuss the use of numerical simulations as tools to optimize the development of high efficiency, reproducible, and stable SERS substrates.