High-resolution and large-strain distributed dynamic sensor based on Brillouin and Rayleigh scattering

A wide-dynamic-range and high-resolution optical fiber sensor based on Brillouin and Rayleigh scattering is proposed, which merges frequency-scanning phase-sensitive optical time-domain reflectometry (Φ-OTDR) and Brillouin optical time domain analysis (BOTDA) via an adaptive signal corrector (ASC). The ASC suppresses the accumulated error of Φ-OTDR with the reference of BOTDA, which breaks through the measurement range limitation of Φ-OTDR so that the proposed sensor can perform a high-resolution measurement in a wide dynamic range. Its measurement range is determined by BOTDA, and can reach the limitation of optical fiber, while the resolution is limited by Φ-OTDR. In proof-of-concept experiments, a maximum strain variation of up to 302.9 µε is measured with a resolution of 5.5 nε. Furthermore, with an ordinary single-mode fiber, high-resolution dynamic pressure monitoring in the range from 20 MP to 0.29 MPa is also demonstrated with 0.14-kPa resolution. This research represents the first time, to the best of our knowledge, that a solution for merging data from a Brillouin sensor and a Rayleigh sensor which achieves the advantages of the two sensors at the same time has been realized.