The fiber temperature sensor with PDMS sensitization based on the T-MFM fiber structure

Abstract The fiber-optic sensor with Taper-MMF-FCF-MMF (T-MFM-F) structure wrapped in PDMS was proposed, which possessed high temperature sensitivity. The fiber-optic sensor consists of a single-mode fiber (SMF), a multi-mode fiber (MMF) and four-core fiber (FCF) with a tapered area in the middle region. The FCF was used to introduce the multipath interference, and more cladding modes were excited through the tapered region, which leaded to the higher extinction ratio of the sensor. The temperature sensing sensitivity of the sensor at 70 ℃ is 0.046 dB/℃. The simulation and experimental results show that this structure has a stronger evanescent field than that of the MFM fiber structure. The sensitivity of 0.284 dB/℃ was obtained in the temperature range of 45–80 ℃ after sensitizing the sensing area with polydimethylsiloxane (PDMS). The temperature sensitivity of the sensors is about 6 times as much as the sensitivity of the original sensor, which was greatly improved by the sensitizing PDMS.