Phase demodulation of hybrid 3×3 coupler and Sagnac interferometer for φ-OTDR

A hybrid phase demodulation structure combining a 3 × 3 coupler and Sagnac interferometer is proposed to improve the spatial resolution and phase demodulation performance of the phase-sensitive optical time-domain reflectometer (φ-OTDR). Through: (1) identical optical path lengths in forward/reverse...

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Main Authors: Binyuan Yang, Tingyu Wang, Jianzhong Zhang, Zhe Ma, Xiang He, Lipu Liu, Yixuan Wang, Mingjiang Zhang
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-07-01
Series:Frontiers in Physics
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Online Access:https://www.frontiersin.org/articles/10.3389/fphy.2025.1609493/full
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author Binyuan Yang
Binyuan Yang
Tingyu Wang
Jianzhong Zhang
Jianzhong Zhang
Zhe Ma
Zhe Ma
Xiang He
Xiang He
Lipu Liu
Lipu Liu
Yixuan Wang
Yixuan Wang
Mingjiang Zhang
Mingjiang Zhang
author_facet Binyuan Yang
Binyuan Yang
Tingyu Wang
Jianzhong Zhang
Jianzhong Zhang
Zhe Ma
Zhe Ma
Xiang He
Xiang He
Lipu Liu
Lipu Liu
Yixuan Wang
Yixuan Wang
Mingjiang Zhang
Mingjiang Zhang
author_sort Binyuan Yang
collection DOAJ
description A hybrid phase demodulation structure combining a 3 × 3 coupler and Sagnac interferometer is proposed to improve the spatial resolution and phase demodulation performance of the phase-sensitive optical time-domain reflectometer (φ-OTDR). Through: (1) identical optical path lengths in forward/reverse Sagnac paths resolving spatial resolution degradation caused by optical path differences in conventional schemes (e.g., 3 × 3 demodulation with unbalanced Michelson or Mach-Zehnder interferometers), and (2) SOA integration dynamically adjusting phase difference between paths to enhance signal-to-noise ratio (SNR) of three output signals, this design achieves high phase demodulation quality. Through theoretical analysis and numerical simulation, the performance enhancement effect of this structure has been verified. The results indicate that the SOA modulates the phase offset of the three output signals, significantly improving the phase demodulation quality and extending the amplitude and frequency response range of the system. Compared with the positioning results achieved by the unbalanced Michelson scheme, this method offers higher spatial resolution. Fundamentally, the structure eliminates path-imbalance limitations via Sagnac symmetry while SOA-driven SNR enhancement ensures robust performance.
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institution Kabale University
issn 2296-424X
language English
publishDate 2025-07-01
publisher Frontiers Media S.A.
record_format Article
series Frontiers in Physics
spelling doaj-art-1b8a590e3a90450cb0356b3fea62c7ee2025-08-20T03:33:22ZengFrontiers Media S.A.Frontiers in Physics2296-424X2025-07-011310.3389/fphy.2025.16094931609493Phase demodulation of hybrid 3×3 coupler and Sagnac interferometer for φ-OTDRBinyuan Yang0Binyuan Yang1Tingyu Wang2Jianzhong Zhang3Jianzhong Zhang4Zhe Ma5Zhe Ma6Xiang He7Xiang He8Lipu Liu9Lipu Liu10Yixuan Wang11Yixuan Wang12Mingjiang Zhang13Mingjiang Zhang14Key Laboratory of Advanced Transducers and Intelligent Control Systems (Ministry of Education and Shanxi Province), Taiyuan University of Technology, Taiyuan, Shanxi, ChinaCollege of Physics and Optoelectronic Engineering, Taiyuan University of Technology, Taiyuan, ChinaDepartment of Physics, Taiyuan Normal University, Taiyuan, Shanxi, ChinaKey Laboratory of Advanced Transducers and Intelligent Control Systems (Ministry of Education and Shanxi Province), Taiyuan University of Technology, Taiyuan, Shanxi, ChinaCollege of Physics and Optoelectronic Engineering, Taiyuan University of Technology, Taiyuan, ChinaKey Laboratory of Advanced Transducers and Intelligent Control Systems (Ministry of Education and Shanxi Province), Taiyuan University of Technology, Taiyuan, Shanxi, ChinaCollege of Physics and Optoelectronic Engineering, Taiyuan University of Technology, Taiyuan, ChinaKey Laboratory of Advanced Transducers and Intelligent Control Systems (Ministry of Education and Shanxi Province), Taiyuan University of Technology, Taiyuan, Shanxi, ChinaCollege of Physics and Optoelectronic Engineering, Taiyuan University of Technology, Taiyuan, ChinaKey Laboratory of Advanced Transducers and Intelligent Control Systems (Ministry of Education and Shanxi Province), Taiyuan University of Technology, Taiyuan, Shanxi, ChinaCollege of Physics and Optoelectronic Engineering, Taiyuan University of Technology, Taiyuan, ChinaKey Laboratory of Advanced Transducers and Intelligent Control Systems (Ministry of Education and Shanxi Province), Taiyuan University of Technology, Taiyuan, Shanxi, ChinaCollege of Physics and Optoelectronic Engineering, Taiyuan University of Technology, Taiyuan, ChinaKey Laboratory of Advanced Transducers and Intelligent Control Systems (Ministry of Education and Shanxi Province), Taiyuan University of Technology, Taiyuan, Shanxi, ChinaCollege of Physics and Optoelectronic Engineering, Taiyuan University of Technology, Taiyuan, ChinaA hybrid phase demodulation structure combining a 3 × 3 coupler and Sagnac interferometer is proposed to improve the spatial resolution and phase demodulation performance of the phase-sensitive optical time-domain reflectometer (φ-OTDR). Through: (1) identical optical path lengths in forward/reverse Sagnac paths resolving spatial resolution degradation caused by optical path differences in conventional schemes (e.g., 3 × 3 demodulation with unbalanced Michelson or Mach-Zehnder interferometers), and (2) SOA integration dynamically adjusting phase difference between paths to enhance signal-to-noise ratio (SNR) of three output signals, this design achieves high phase demodulation quality. Through theoretical analysis and numerical simulation, the performance enhancement effect of this structure has been verified. The results indicate that the SOA modulates the phase offset of the three output signals, significantly improving the phase demodulation quality and extending the amplitude and frequency response range of the system. Compared with the positioning results achieved by the unbalanced Michelson scheme, this method offers higher spatial resolution. Fundamentally, the structure eliminates path-imbalance limitations via Sagnac symmetry while SOA-driven SNR enhancement ensures robust performance.https://www.frontiersin.org/articles/10.3389/fphy.2025.1609493/fulldistributed acoustic sensingSagnac interferometerspatial resolutionamplitudefrequency responsephase demodulation
spellingShingle Binyuan Yang
Binyuan Yang
Tingyu Wang
Jianzhong Zhang
Jianzhong Zhang
Zhe Ma
Zhe Ma
Xiang He
Xiang He
Lipu Liu
Lipu Liu
Yixuan Wang
Yixuan Wang
Mingjiang Zhang
Mingjiang Zhang
Phase demodulation of hybrid 3×3 coupler and Sagnac interferometer for φ-OTDR
Frontiers in Physics
distributed acoustic sensing
Sagnac interferometer
spatial resolution
amplitudefrequency response
phase demodulation
title Phase demodulation of hybrid 3×3 coupler and Sagnac interferometer for φ-OTDR
title_full Phase demodulation of hybrid 3×3 coupler and Sagnac interferometer for φ-OTDR
title_fullStr Phase demodulation of hybrid 3×3 coupler and Sagnac interferometer for φ-OTDR
title_full_unstemmed Phase demodulation of hybrid 3×3 coupler and Sagnac interferometer for φ-OTDR
title_short Phase demodulation of hybrid 3×3 coupler and Sagnac interferometer for φ-OTDR
title_sort phase demodulation of hybrid 3 3 coupler and sagnac interferometer for φ otdr
topic distributed acoustic sensing
Sagnac interferometer
spatial resolution
amplitudefrequency response
phase demodulation
url https://www.frontiersin.org/articles/10.3389/fphy.2025.1609493/full
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