SPR Dual-Parameter Sensor With Ag/MoS₂ Composite Film for Refractive Index Detection in High-Temperature Environment

In order to cope with the crosstalk between temperature and refractive index (RI) caused by high-temperature environments, this study proposes to modify the surface plasmon resonance (SPR) fiber optic sensors with molybdenum disulfide (MoS2). MoS2 efficiently modulates the resonance wavelength, enabling the sensor to operate in high-temperature environments. The effect of MoS2 film thickness on the resonance wavelength was investigated by depositing MoS2 film on the surface of no-core fiber (NCF) using the magnetron sputtering method. The analysis shows that MoS2 can induce a significant redshift of the resonance dip, and the degree of redshift is related to the film thickness. In addition, a dual-parameter SPR sensor capable of detecting RI at high temperatures was prepared in this work by selecting the optimal Ag film thickness and MoS2 film thickness. The sensor was obtained by cascading an Ag-based NCF with an Ag/MoS2-based NCF, which was simulated and tested experimentally. The results show that the maximum temperature sensitivity is 4.3 nm/°C over the 50 °C–90 °C temperature range. The maximum RI sensitivity is 5243.4 nm/RIU over the RI range of 1.333–1.395. The test results also show that the two channels of the sensor are independent of each other and have good stability. Therefore, Ag/MoS2-based SPR sensors have the advantages of adjustable bandwidth, dual-parameter independent detection, and high sensitivity. These are essential in the future fields of multiparameter sensing, compensated detection, and real-time biomonitoring.