Simultaneous measurement of temperature and refractive index based on plastic optical fiber knots and F–P interferometer

Abstract

A reflective sensor based on F–P interferometer (FPI) and plastic optical fiber (POF) knots is proposed for simultaneously measuring the temperature and refractive index (RI). The FPI is fabricated by curing a polyvinyl chloride film on the end of a POF, and it is used to detect the temperature shifts. Meanwhile, the high sensitivity measurement of RI of the glucose solution is realized based on the POF knots. Finally, the RI and temperature are detected simultaneously with the help of the wavelength and reflected light intensity of an interference peak. The experimental results indicate that the proposed sensor achieves a maximum RI sensitivity of 2381.73%/RIU in the RI range of 1.33–1.374, and it can detect temperature simultaneously. The maximum relative deviations between the measured results and actual values of RI and temperature are only 0.038% and 2.76% respectively, and they have good repeatability. Furthermore, the proposed sensor has potential applications in biochemistry and food safety monitoring due to the unmodified and simple preparation process.