Silica microdisk-based plasmonic whispering-gallery modes for refractive index and temperature sensing

In this paper, we propose and investigate plasmonic whispering-gallery modes (WGMs) based on a silica microdisk coated with a gold film and a UV-glue film in sequence, which could be utilized for the simultaneous sensing of refractive index (RI) and temperature. The silica microdisk is coated with the gold film on its upper surface and lateral surface, followed by a layer of UV glue only on the upper surface. The two plasmonic WGMs are excited at the same time, and their two polarization directions are perpendicular to each other. The plasmonic WGM in the vertical polarization direction primarily distributes in the glue film, which can sensitively respond to the temperature and RI perturbations. The plasmonic WGM in the horizontal polarization direction mainly distributes in the lateral side of the microdisk and only responds to the RI, without a response on the temperature sensing. It could be utilized as a compensating component to demodulate the RI and temperature parameters. The sensitivities of temperature and RI could be up to −35.3pm/ ∘ C and 92.2 nm/RIU, respectively.