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Proceedings Paper

Fast Sinusoidal Frequency Scan OFDR for Long Distance Distributed Acoustic Sensing
Author(s): Lihi Shiloh; Avishay Eyal
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Paper Abstract

Implementation of Optical Frequency Domain Reflectometry (OFDR) requires a source whose instantaneous frequency can be accurately scanned over a sufficiently wide frequency range. Achieving high repetition rates of accurate linear frequency sweeps can be rather challenging. In contrast, fast and accurate Sinusoidal Frequency Scan (SFS-OFDR) can be easily implemented via direct or external optical frequency modulation. While enabling high spatial resolution measurements of a sensing fiber at high scan rates, SFS-OFDR requires a special processing algorithm to convert the detector output to fiber profiles. Previous implementation of the algorithm involved O(N2) complexity and prohibited real time operation. In this work a novel algorithm for processing SFS-OFDR raw data is introduced. Based on two consecutive FFT operations, the algorithm produces the fiber profile with O(NlogN) operations and lends itself for real time applications. The new method was tested via simulation and experiment. It enabled static detection with high resolution (~3m) at 64km and highly sensitive dynamic detection (stretching amplitude of 70nm) near the end of a 64km sensing fiber with spatial resolution <10m and with 400Hz scan repetition rate.

Paper Details

Date Published: 23 April 2017
PDF: 4 pages
Proc. SPIE 10323, 25th International Conference on Optical Fiber Sensors, 103230P (23 April 2017); doi: 10.1117/12.2265403
Show Author Affiliations
Lihi Shiloh, Tel Aviv Univ. (Israel)
Avishay Eyal, Tel Aviv Univ. (Israel)

Published in SPIE Proceedings Vol. 10323:
25th International Conference on Optical Fiber Sensors
Youngjoo Chung; Wei Jin; Byoungho Lee; John Canning; Kentaro Nakamura; Libo Yuan, Editor(s)

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