Low-cost temperature- And strain-insensitive twist sensor based on a hybrid fiber grating structure

Abstract

We proposed and experimentally demonstrated a temperature- and strain-insensitive twist sensor based on a hybrid fiber grating structure, in which the hybrid grating structure is constructed with a 45°-tilted fiber grating and a chirped fiber Bragg grating UV-inscribed in a single-mode fiber in series. The sensing performance has been evaluated by experimental and numerical analyses, which are in good consistency. The experimental results show that the hybrid-grating-structure-based twist sensor has a maximum twist sensitivity up to 15.037 dB/rad. Moreover, due to the invariability of the fiber birefringence and the state of polarization of the input light, such sensor has intrinsically low temperature and strain sensitivities of 7.86 × 10−3 dB∕°C and 6.7 × 10−5 dB∕με, corresponding to the maximum twist measurement error resulting from temperature and strain of 5.2 × 10−4 rad∕°C and 4.5 × 10−6 rad∕με, respectively.