10-cm spatial resolution distributed acoustic sensor based on an ultra low-loss enhanced backscattering fiber
Ali Masoudi, Timothy Lee, Martynas Beresna, Gilberto Brambilla
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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mn>1.9</mml:mn> <mml:mspace width="thinmathspace"/> <mml:mi>n</mml:mi> <mml:mi>ε</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:msqrt> <mml:mi>H</mml:mi> <mml:mi>z</mml:mi> </mml:msqrt> </mml:math> over 1 km sensing range.