Ultrasharp LSPR Temperature Sensor Based on Grapefruit Fiber Filled With a Silver Nanoshell and Liquid

Abstract

A grapefruit fiber (GF) based temperature sensor with ultrasharp localized surface plasmon resonance (LSPR) is designed and characterized by finite element method. The silver nanoshell (SNS), formed by a dielectric core and a silver shell together with chloroform own large thermo-optic coefficient is sealed into one large air hole of the GF as the core sensing region. Benefiting from the plasmon hybridization in SNS and birefringence, the designed sensor can support two separate ultrasharp resonance peaks with full width half maximum (FWHM) only 4.6 nm in orthogonal polarizations, which is the narrowest to our best knowledge and the highest figure of merit (FOM) of 0.43/°C can be obtained. Results show that by following the shifts of two polarized peaks, dual channel temperature sensing can be realized simultaneously at 5 °C–55 °C with the maximum sensitivity of −17.8 nm/°C and −17.2 nm/°C, about 3–17 times higher than other same type works. Moreover, the influences of structure parameters of SNS like deposition position, number, diameter, and length on the sensing performances are discussed in detail.