Torsion-Assisted FBG With an Enhanced Capability of High-Temperature Sensing

We propose a simple and effective strategy to improve the high-temperature sensing characteristics of fiber Bragg gratings (FBGs) by introducing compressive stress into the grating structure by means of torsion assisted. Specifically, comparative analysis reveals that the torsion-assisted FBG has exhibited better high-temperature stability within the temperature range of 200∼800 °C as evidenced by a decay rate of 0.0064 dB/°C, which is significantly lower than the bare FBG (0.0081 dB/°C). Careful investigation shows that the thermal decay of the FBG can be further mediated by regulating the applied torsion and the simulation analysis has demonstrated that applied torsion can effectively introduce compressive stresses into the grating. Moreover, the torsion-assisted FBG also shows better high-temperature wavelength stability, slower heating decay rate, and improved wavelength hysteresis. In addition, the high-temperature strain characteristics of the torsion-assisted FBGs have also been investigated. Given the merits such as easy implementation, no need for complex heat treatment processes, good controllability, and low cost, we envision that the torsion-assisted FBG is promising in the field of high-temperature sensing.