Sensitive surface-enhanced Raman scattering active substrate based on gap surface plasmon polaritons

Abstract

The authors fabricate three types of surface-enhanced Raman scattering (SERS) active substrates by nanoimprint lithography and experimentally investigated the intensity enhancement of Raman scattering induced by gap surface plasmon polaritons (GSPPs). An area-averaged Raman signal enhancement factor of 1.1 × 107 can be achieved by the GSPPs structures for monolayer thiophenol molecules absorbed on silver surfaces, compared with 6.2 × 105 of conventional SERS-active substrates. The exceptional field enhancement originates not only from the localized surface plasmon polaritons but also from the coupling between the GSPPs at two metal/dielectric interfaces. These structures are expected to find promising applications as SERS devices in trace-level molecular detection and identification.