10-cm spatial resolution distributed acoustic sensor based on an ultra low-loss enhanced backscattering fiber

Abstract

In this work, a distributed acoustic sensor (DAS) with 10-cm spatial resolution is demonstrated. Such a high resolution is achieved by employing an ultra low-loss enhanced backscattering (ULEB) fiber as a sensing element. A conventional DAS system is modified to interrogate the ULEB fiber comprised of 50 discrete reflectors with an average reflectance of −56 dB. The ULEB fiber was fabricated with an automated reel-to-reel inscription machine, modified to create more uniform reflectors with similar reflectivity in the core of the fiber. The sensing arrangement exhibits a phase noise of 1.9 nε/√Hz over 1 km sensing range.