Hybridised extraordinary optical transmission in plasmonic cavity

Modification of the spectral response of a periodically coupled metallic nanostructure is reported. A thin SU-8 dielectric cavity was fabricated on a nanopatterned gold film. Additional resonance peaks are observed in the transmitted spectrum due to the interaction between excited surface plasmon polaritons (SPPs) and optical feedback provided by the dielectric cavity. A comparison with transmitted spectra from a planar gold/dielectric cavity configuration confirms the hybridisation of extraordinary optical transmission through interaction between SPPs and optical Fabry-Pérot modes in the cavity.