Millimetric spatial resolution time-expanded φ-OTDR

Time-expanded phase-sensitive optical time-domain reflectometry is a distributed optical fiber sensing technology based on dual-frequency combs that allows for dynamic and high spatial resolution measurements while maintaining reduced detection requirements. Since the formalization of the technique, different experimental schemes have been satisfactorily tested, with a general performance of cm-scale spatial resolution over hundreds of meters. In this article, we present an optimized scheme with enhanced energy and spectral efficiencies that allows reaching 5 mm spatial resolution. As compared to previous experimental approaches, the presented architecture is based on a free-running dual comb setup generated through pure electro-optical phase modulation. Besides, the introduction of an optical hybrid in the detection stage allows for doubling the spatial resolution while keeping the refresh rate and the sensing range unchanged.(c) 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(http://creativecommons.org/licenses/by/4.0/).

Automated summary

Time-expanded phase-sensitive optical time-domain reflectometry is a distributed optical fiber sensing technology that enables high spatial resolution measurements. An optimized scheme with enhanced energy and spectral efficiencies, as well as the introduction of an optical hybrid, allows for achieving a spatial resolution of 5 mm.