Temperature-independent evanescent wave sensor made of a stress-released silica optical fiber taper

Based on a cyclic heating-cooling treatment method, a temperature-independent silica optical fiber evanescent wave sensor is proposed. The cyclic heating-cooling treatment process could significantly release the residual stresses in the taper, achieving a high measurement accuracy in the temperature range of 20-200 °C. After the treatment, the relative light intensity1 (RLI) variation was 0.03 dB in the temperature range of 20-200 °C. The RLI variation of the tapered silica fiber-optic evanescent wave2 (TSFEW) sensor was reduced by 86% compared with the untreated TSFEW sensor. Two kinds of typical treatment processes were studied by contrast experiments to further explore effective treatment process of temperature-independent TSFEW sensors. The effectiveness of the temperature-independent TSFEW sensor was validated using sucrose solutions at different temperatures. The mechanism of cyclic heating-cooling treatment method for eliminating the effect of temperature on TSFEW sensors was analyzed.