High-Spatial-Resolution High-Accuracy OFDR Distributed Sensors Based on Seamless fs-WFBG Array

Due to the limit of the random optical noise in Rayleigh backscattering and the sliding window length, there is a trade-off between sensing spatial resolution and accuracy in optical frequency domain reflectometry (OFDR). This paper proposes a novel high-spatial-resolution high-accuracy OFDR distributed sensors based on seamless femtosecond weak fiber Bragg grating (WFBG) array. Using femtosecond laser point-by-point (PbP) inscription technology, a 5 cm long seamless weak grating array was successfully fabricated on a polyimide fiber, consisting of ten 5 mm long WFBGs. Experimental results demonstrate that a sensing spatial resolution of 533 μm and a wavelength demodulation accuracy of ±2.23 pm were achieved for the first time.