Liquid refractive index and temperature sensor using multimode interference-based corroded polarization-maintaining fiber

A cost-efficient multimode interference-based sensor with corroded polarization-maintaining fiber (PMF) is proposed and experimentally demonstrated for the measurement of liquid refractive index (RI) and temperature. The sensor consists of a segment of corroded PMF and two segments of multimode fiber (MMF). Two segments of MMF, which are used as beam splitter and combiner are embedded on both ends of the PMF. The all-fiber sensor is put in the middle of the single-mode fiber. The RI and temperature characteristics of the sensor are investigated experimentally. The results show that two resonant peaks have different spectral responses of RI and temperature changes, which indicate that the sensor can realize simultaneous RI and temperature measurements. The experimental result shows that the high RI sensitivity is up to 318.279 nm/RIU in the RI range from 1.333 to 1.350 and the high temperature sensitivity is 0.188 nm/degrees C in the range from 20 degrees C to 40 degrees C. This sensor exhibits the advantages of low cost and high sensitivity and may have potential application in RI and temperature measurements. (C) 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)