Ultrahigh-sensitivity SPR fiber temperature sensor based Ge2Sb2Te5 and cyclohexane

Abstract

High-sensitivity fiber optic temperature sensors are essential analytical tools in biological and chemical fields. To increase the temperature sensitivity of the surface plasmon resonance sensors, we decide to employ a stable material, Ge2Sb2Te5 (GST). When GST is deposited on the gold film's surface, SPR is excited at lower frequency, this indicates that the resonance dips are red-shifted. At long wavelengths, the evanescent field is greatly enhanced, and the penetration depth is increased, which increases the interaction volume. In other words, the sensitivity is greatly improved. The fiber optic is encapsulated in cyclohexane with a high thermo-optic coefficient and a high refractive index. The sensitivity improves further because the fiber is placed in a high refractive index environment. The sensor's average temperature sensitivity is 14.7 nm/°C, with a measurement range of 5 °C to 80 °C, according to the output spectra. The maximum temperature sensitivity can reach 25.7 nm/°C. As a result, the suggested temperature sensor might be useful in various industries that need high measurement precision.