Dielectric layer thickness insensitive EVA/Ag-coated hollow fiber temperature sensor based on long-range surface plasmon resonance.

A novel hollow fiber temperature sensor (HFTS) based on long-range surface plasmon resonance is presented. The HFTS consists of a dielectric/Ag-coated hollow fiber filled with the thermosensitive liquid and two multimode fibers connected at both ends. By measuring the transmission spectra under different temperatures, the performances, including sensitivity and figure of merit (FOM) of the sensors with different structural parameters, such as thermosensitive liquid property, ethylene-vinyl acetate (EVA) and silver layer thicknesses, were investigated experimentally. The results shows that the sensitivity of the optimized HFTS is 1.60nm/°C to 5.21nm/°C in the range from 20°C to 60°C, and the FOM is up to 0.0453°C ^-1 . Both performances are higher than most reported optical fiber temperature sensors based on surface plasmon resonance. Moreover, the performance of the HFTS is not sensitive to the dielectric layer thickness, which greatly reduces the difficulty of fabrication.