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Proceedings Paper

Quantitative multimode fiber acoustic sensors (Conference Presentation)
Author(s): Matthew J. Murray; Allen Davis; Clay Kirkendall; Brandon Redding

Paper Abstract

Here we propose and demonstrate an optical time-domain reflectometry (OTDR) system that uses multimode fiber to make quantitative acoustic measurements that are immune to signal fading. The vast majority of OTDR fiber sensors use single mode fiber, which are limited by signal fading and by low light levels. Sensing with multimode fiber has the potential to overcome both of these limitations. First, multimode fiber sensors are immune to signal fading by simultaneously detecting many spatial modes. Second, multimode fiber sensors can use increased light levels due to a higher threshold for non-linear effects. Combined with a higher capture fraction of Rayleigh scattered light, this enables multimode fiber sensors to detect higher light levels and exhibit lower noise. We demonstrate new methods that use off-axis holography to recover quantitative strain information from the time-dependent backscattered speckle field. The multimode fiber sensor exhibits a linear response, a bandwidth of 20 kHz, and has a noise level better than 6 pε/√Hz. This work represents the first multimode fiber OTDR systems that take full advantage of the unique features of multimode fiber for acoustic sensing.

Paper Details

Date Published: 14 May 2019
Proc. SPIE 11000, Fiber Optic Sensors and Applications XVI, 110000L (14 May 2019); doi: 10.1117/12.2518926
Show Author Affiliations
Matthew J. Murray, U.S. Naval Research Lab. (United States)
Allen Davis, U.S. Naval Research Lab. (United States)
Clay Kirkendall, U.S. Naval Research Lab. (United States)
Brandon Redding, U.S. Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 11000:
Fiber Optic Sensors and Applications XVI
Robert A. Lieberman; Glen A. Sanders; Ingrid U. Scheel, Editor(s)

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