A Dual-Channel Surface Plasmon Resonance Sensor for the Liquid Refractive Index and Temperature Measurement Based on Hollow-Core Fiber

We propose a dual-channel surface plasmon resonance (SPR) sensor based on hollow-core fiber (HCF) for the simultaneous measurement of the liquid refractive index (RI) and ambient temperature. The simultaneous monitoring of two parameters can effectively realize the temperature compensation of liquid RI measurement. One channel is coated with a silver film to sense the liquid RI, the other channel is coated with a gold film and polydimethylsiloxane (PDMS) to sense the ambient temperature, and the cross sensitivity of the multi-parameter measurement is solved using the dual-wavelength matrix method. The sensing performance of the proposed sensor is investigated both theoretically and experimentally, which proves that it can achieve high sensitivity in a relatively wide measurement range. The experiment shows that the liquid RI sensitivity is as high as 2400.079 nm/RIU in the RI range of 1.3333–1.3770, and the temperature sensitivity is −1.29 nm/°C in the temperature range of 40 °C–90 °C. This work provides a new scheme for the multi-parameter measurement, and the proposed sensor has the advantages of simple and compact structure, low cost, wide measurement range and high sensitivity, which promises broad application prospects in the simultaneous monitoring of liquid RI and temperature.