This paper presents a novel phase-sensitive optical time-domain reflectometry (ФOTDR) approach that achieves centimeter-scale spatial resolutions over 1 km using a low detection bandwidth in the MHz regime. This is accomplished through a customized time expansion of the received optical traces using dual-comb spectrometry and random phase-spectral coding to maximize signal-to-noise ratio. The method offers a significant improvement over traditional ФOTDR, which requires GHz bandwidths for high resolutions, thus reducing system cost and complexity. The authors compare their approach with existing methods and analyze the trade-offs involved, suggesting potential applications in metrology, borehole monitoring, and aerospace.

Miguel Soriano-Amat, Hugo F. Martins, Vicente Durán, Luis Costa, Sonia Martin-Lopez, Miguel Gonzalez-Herraez, María R. Fernández-Ruiz