Highly sensitive temperature sensor based on the reciprocal thermal responses of cascaded dual-cavities

Abstract

A highly sensitive fiber temperature sensor based on cascaded multimode fiber cavity and polymer cavity between single mode fibers was proposed. A three-beam Fabry-Pérot interferometer was obtained. We demodulated the interference spectrum by means of the fast Fourier transform and the signal filtering. As the thermal response of the polymer cavity and the multimode fiber cavity are negative and positive, respectively, the high temperature sensitivity can be achieved by a subtraction between the two reciprocal thermal responses. Experimental results show that the sensitivity of the temperature sensor is as high as 2.95 nm/°C in the measurement range between −15 °C and 35 °C. The proposed sensor may find widespread application in biomedicine and environmental science due to its simple preparation method and high sensitivity.