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 (MoS ₂ ). MoS ₂ efficiently modulates the resonance wavelength, enabling the sensor to operate in high-temperature environments. The effect of MoS ₂ film thickness on the resonance wavelength was investigated by depositing MoS ₂ film on the surface of no-core fiber (NCF) using the magnetron sputtering method. The analysis shows that MoS ₂ 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 MoS ₂ film thickness. The sensor was obtained by cascading an Ag-based NCF with an Ag/MoS ₂ -based NCF, which was simulated and tested experimentally. The results show that the maximum temperature sensitivity is 4.3 nm/°C over the 50-90 °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/MoS ₂ -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.