High-Sensitivity Temperature Sensor Based on Thin Film Coating and Lossy Mode Resonance

Lossy mode resonance (LMR) combined with side-polished fibers and thin film coatings were used to fabricate a high-sensitivity temperature sensor. Tin dioxide (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SnO}_{2}$</tex>) thin film was deposited on the side-polished surface of the single-mode fiber using electron beam evaporation technology. By controlling the residual thickness of the side-polished fibers and the thickness of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SnO}_{2}$</tex> thin film. Ambient temperature measurement range is from 30° C to 150° C. The experimental results show that the maximum resonant wavelength shift of 171.72 nm was observed by the LMR-based fiber optic temperature sensor. The highest sensitivity of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.61 \text{nm} /{ }^{\circ} \mathrm{C}$</tex> was achieved in the temperature range of 30150° C.