Temperature insensitive torsion sensor based on ring-core fiber orthogonal core-offset structure

Abstract

We have proposed a temperature-insensitive fiber-optic torsion sensor based on ring-core fiber (RCF). The sensor is fabricated by orthogonal core-offset splicing between the RCF and single-mode fiber. Due to the core-offset structure, the Mach-Zehnder interference is enhanced, and the torsion sensing is realized. The sensor is fabricated and tested, exhibit high linear torsion sensitivity of −0.2 nm/(rad/m) in the range of 0–28.5599 rad/m and −0.079 nm/(rad/m) in the range of −25.3866–0 rad/m. The torsion increasing and decreasing process proves the good reliability of our sensor. Besides, through the temperature sensing, it is found that our sensors show a low temperature sensitivity of 26.4 pm/°C in the temperature range from 30 °C to 90 °C, which reduces the cross-sensitivity between torsion and temperature. Thus, the sensor can be used in structural conventional health monitoring, biomechanics due to many advantages such as sample size, low-cost and high sensitivity.