Optical Cavity-Enhanced Localized Surface Plasmon Resonance for High-Quality Sensing

Abstract

We report an effective strategy to enhance the localized surface plasmon resonances (LSPRs) of metallic nanoparticles by introducing a Fabry-Pérot (FP) cavity for high-quality sensing. The concept is based on the combined excitation of LSPRs in metallic nanoparticles and optical cavity modes supported by the FP cavities, whose strong interactions result in two ultra-narrowband hybridized plasmon modes with a huge electric field enhancement. A high-quality double-band plasmonic nanosensor, with the refractive index sensitivity approaching 600 nm/RIU and a figure of merit exceeding 28 is achieved here, which suggests that the cavity-coupling strategy could offer new perspectives for achieving ultra-compact efficient biosensors.