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

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 degrees C is 0.046 dB/degrees C. 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/degrees C was obtained in the temperature range of 45-80 degrees C 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.

Automated summary

The proposed fiber-optic sensor with Taper-MMF-FCF-MMF (T-MFM-F) structure wrapped in PDMS has high temperature sensitivity. By introducing a tapered area and sensitizing with PDMS, the sensor achieved a temperature sensitivity about 6 times higher than the original sensor. The structure excites more cladding modes, resulting in a higher extinction ratio and stronger evanescent field compared to the MFM fiber structure.