Interference fading suppression in φ-OTDR using space-division multiplexed probes

Zhao, Zhiyong; Wu, Huan; Hu, Junhui; Zhu, Kun; Dang, Yunli; Yan, Yaxi; Tang, Ming; Lu, Chao

doi:10.1364/oe.422608

Cited by 48 publications

(13 citation statements)

References 27 publications

(16 reference statements)

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“…Through such calculations, the evolution of the DOP is shown in Figure 5. The DOP converges to 1/3 when the accumulated measurement time is 2500 s. This result confirms the validity of the theoretical prediction in Equation (17).…”

Section: Temporal Depolarization Measurementsupporting

confidence: 87%

Polarization Properties of Coherently Superposed Rayleigh Backscattered Light in Single-Mode Fibers

Dong,

Zhang,

2023

Sensors

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The properties of the state of polarization (SOP) and the degree of polarization (DOP) of Rayleigh backscattered light (RBL) in single-mode fibers (SMF) are investigated theoretically and experimentally when the incident probe is a perfectly coherent continuous-wave (CW) light. It is concluded that the instantaneous DOP of the coherently superposed RBL is always 100%, and the instantaneous SOP is determined by the distributions of the birefringence and the optical phase along the SMF. Therefore, the instantaneous SOP of the coherently superposed RBL does not have a constant relationship with the SOP of the incident CW probe. Furthermore, the instantaneous SOP varies randomly with time because the optical phase is very sensitive to ambient temperature and vibration even in the lab environment. Further theoretical derivation and experimental verification demonstrate, for the first time, that the temporally averaged SOP of the coherently superposed RBL has a simple constant relationship with the SOP of the incident CW probe, and the temporally averaged DOP is 1/3 in an SMF with low and randomly distributed birefringence. The derived formulas and obtained findings can be used to enhance the modelling and improve the performances of phase-sensitive optical time-domain reflectometry and other Rayleigh backscattering based fiber-optic sensors.

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Section: Temporal Depolarization Measurementsupporting

confidence: 87%

Polarization Properties of Coherently Superposed Rayleigh Backscattered Light in Single-Mode Fibers

Dong,

Zhang,

2023

Sensors

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“…The first kind generally known as interference fading is a phenomenon of Rayleigh scattering itself. It is caused by non-uniform positions of scattering centers within the optical fiber and is a topic of active research 16 , 17 . The second kind, known as polarization mismatch fading or simply polarization fading, depends on interferometric conditions for coherent heterodyne detection 11 .…”

Section: Introductionmentioning

confidence: 99%

Phase-sensitive optical time domain reflectometry based on geometric phase measurement

Shaheen

Hicke²,

Krebber³

2023

Sci Rep

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A phase-sensitive optical time domain reflectometer based on coherent heterodyne detection of geometric phase in the beat signal of light, is reported for the first time to our knowledge. The use of the geometric phase to extract strain makes it immune to polarisation diversity fading. This is because a polarisation mismatch between the interfering beams is not a hindrance to its measurement. The geometric phase is calculated using the amplitude of the beat signal and individual beam intensities without any need for phase unwrapping. It is measured per beat period and can be equated with the traditionally measured dynamic phase with appropriate scaling. The results show that the system based on the geometric phase successfully measures strain, free from polarisation mismatch fading and phase unwrapping errors, providing a completely novel solution to these problems.

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“…In term of special optical fiber, in 2017, X. Zhang et al by used uwFBGs structure in Ф-OTDR system, obtaining the signal-to-noise ratio of 56 dB [1] . In 2021, Z. Zhao et al used the few-mode fiber as the sensing element of the heterodyne Ф-OTDR system to multiplex RBS signals in different modes, to suppress the interference fading effect [2] . In terms of demodulation algorithms, in 2019, Y. Wu et al proposed a spectrum extraction and remixing scheme, using single rectangular probe pulse to eliminate interference fading of Ф-OTDR system [3] .…”

Section: Introductionmentioning

confidence: 99%

A high fidelity Ф-OTDR system based on compact and flexible multi-frequency probe pulse modulation

Lei,

Chen,

et al. 2023

AOPC 2023: Optic Fiber Gyro

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In this paper, we propose a high fidelity phase-sensitive optical time-domain reflectometer (Ф-OTDR) system based on compact and flexible multi-frequency probe pulse modulation. Single-frequency continuous light is multi-frequency modulated by a broadband acousto-optic modulator (AOM) loaded with multiple microwave signals of different frequencies, finally, multiple Rayleigh backscattered (RBS) optical signals with different intensity distributions can be obtained by a single acquisition, and the most accurate signal is always selected for phase reconstruction to achieve the high fidelity Ф-OTDR system, which has the advantages of compact structure, precise control of phase delay, flexible and controllable frequency components, and no sacrificing response bandwidth and spatial resolution, etc. In the experiment Ф-OTDR system, we simultaneously modulate the multi-frequency probe pulse light with a width of 100ns and three non-equidistant frequencies, and inject it into a 2km sensing fiber. The RBS light signal multiplexing results show that the probability of interference fading effect in the system is reduced from 17.541% to 1.123%. And the highfidelity phase information of a 100Hz simulated vibration signal was extracted on a 3km sensing fiber, corresponding to a strain value of about 11.9nε. Distributed optical fiber sensing, phase-sensitive optical time domain reflectometer, interference fading effect.

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Interference fading suppression in φ-OTDR using space-division multiplexed probes

Cited by 48 publications

References 27 publications

Polarization Properties of Coherently Superposed Rayleigh Backscattered Light in Single-Mode Fibers

Polarization Properties of Coherently Superposed Rayleigh Backscattered Light in Single-Mode Fibers

Phase-sensitive optical time domain reflectometry based on geometric phase measurement

A high fidelity Ф-OTDR system based on compact and flexible multi-frequency probe pulse modulation

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