Fundamentals of Optical Fiber Sensing Schemes Based on Coherent Optical Time Domain Reflectometry: Signal Model Under Static Fiber Conditions

Лиокумович, Л. Б.; Ushakov, Nikolai; Котов, О. И.; Bisyarin, M. A.; Hartog, Arthur H.

doi:10.1109/jlt.2015.2449085

Cited by 133 publications

(61 citation statements)

References 33 publications

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“…[9]. In particular, the backscattering process is modelled by a set of discrete scatterers (reflectors) whose amplitude and phase are characterized as statistically independent random Gaussian variables, while their coordinates are deterministic (the random phase of the scatterers contributes to the final backscatter trace as if they had randomly distributed positions).…”

mentioning

confidence: 99%

Phase-sensitive OTDR probe pulse shapes robust against modulation-instability fading

Fernández‐Ruiz

Martins²,

Pastor-Graells

et al. 2016

Opt. Lett.

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Typicalphase-sensitive optical-time domain reflectometry (φOTDR) schemes rely on the use of coherent rectangular-shaped probe pulses. In these systems, there is a trade-off between the signal-to-noise ratio (SNR), spatial resolution and operating range of the φOTDR system. To increase any of these parameters, an increase in the pulse peak power is usually indispensable. However, as it is well-known, there is a limit in the allowable increase in probe power due to the onset of undesired nonlinear effects such as modulation instability. In this Letter, we perform an analysis of the effect of the probe pulse shape on the visibility fading due to modulation instability. In particular, four different temporal profiles are chosen, namely, rectangular, Gaussian, triangular and super-Gaussian (order 2). Our numerical and experimental analyses reveal that the use of triangular or Gaussian-like pulses can significantly inhibit the visibility fading issues. As such, an increase in the range up to two-fold for the same pulse energy (i.e., SNR) and nominal spatial resolution can be achieved, as compared with the results obtained when using rectangular pulses. This is due to a more robust behavior of the Gaussian and triangular pulses against the FermiPasta-Ulam (FPU) recurrence occurring in modulation instability.

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mentioning

confidence: 99%

Phase-sensitive OTDR probe pulse shapes robust against modulation-instability fading

Fernández‐Ruiz

Martins²,

Pastor-Graells

et al. 2016

Opt. Lett.

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“…Rayleigh scattering in a single-mode optical fiber can be described by a simplified model of effective discrete scatterers characterized by their axial positions x j along the fiber and their scattering amplitudes, where the typical spacing ∆x between the positions of neighboring scatterers is larger than an optical wavelength, ∆x λ [1]. Similarly, provided that fiber birefringence is sufficiently small, and assuming a polarization-insensitive optical detector, polarization effects can be neglected [1].…”

Section: Theorymentioning

confidence: 99%

“…Similarly, provided that fiber birefringence is sufficiently small, and assuming a polarization-insensitive optical detector, polarization effects can be neglected [1]. In the following we assume fully polarized, perfectly monochromatic light.…”

Section: Theorymentioning

confidence: 99%

“…F iber-optic coherent optical time-domain Rayleigh backscatter reflectometry (C-OTDR) is the basis of most current approaches [1] to so-called "distributed acoustic sensing" (DAS) and "distributed vibration sensing" (DVS). All varieties of C-OTDR rely on the linear Rayleigh backscattering within an optical fibre that is caused by nanometer-scale inhomogeneities of the refractive index.…”

Section: Introductionmentioning

confidence: 99%

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Random Quadrature Demodulation for Direct Detection Single-Pulse Rayleigh C-OTDR

Rohwetter

Eisermann

Krebber

2016

J. Lightwave Technol.

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We present a demodulation method that partially compensates for the nonlinear and random transfer function of fiber-optic direct detection coherent Rayleigh optical time-domain reflectometry (C-OTDR). Specifically, the proposed method is shown to improve the detection of small amplitude, high frequency dynamic optical fiber strain as it occurs in acoustic emission sensing. The method is applicable provided that the dynamic fiber strain to be sensed is known to affect a longer section of sensing fiber in a spatially homogeneous way. It is shown that this knowledge can be used to extract more quantitative information from the measured C-OTDR signal by averaging signal components from the affected fiber section in a suitable and efficient way. The theoretical basis of the method is developed and supporting experimental results are presented.Index Terms-Optical fiber sensors, coherent optical timedomain reflectometry (C-OTDR), fiber-optic speckle interferometry, remote acoustic emission sensing.

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“…In typical time-domain configurations, a light pulse is sent into the fiber, and a small fraction of the incident light is backscattered towards the emitter. The time of flight of the light pulse in the fiber gives the localization of the backscatter, and the analysis of the local backscatter might reveal information of certain thermal and mechanical fiber properties [24]. Distributed optical fiber sensors have, so far, been demonstrated to be well-suited for the sensing of physical quantities such as temperature or strain.…”

Section: Introductionmentioning

confidence: 99%

Distributed photothermal spectroscopy in microstructured optical fibers: towards high-resolution mapping of gas presence over long distances

García-Ruiz

Pastor-Graells

Martins³

et al. 2017

Opt. Express

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, 2017, "Distributed photothermal spectroscopy in microstructured optical fibers: towards high-resolution mapping of gas presence over long distances", Optics Express, vol.25, n.3, pp. 1789Express, vol.25, n.3, pp. -1805 Available at http://dx.doi.org/10.1364/OE.25.001789 © 2017 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited. Abstract: Chemical sensing using optical fibers is often challenging, as it is generally difficult to achieve strong interaction between the guided light and the analyte at the wavelength of interest for performing the detection. Despite this difficulty, many schemes exist (and can be found in the literature) for point chemical fiber sensors. However, the challenge increases even further when it comes to performing fully distributed chemical sensing. In this case, the optical signal which interacts with the analyte is typically also the signal that has to travel to and from the interrogator: for a good sensitivity, the light should interact strongly with the analyte, leading inevitably to an increased loss and a reduced range. Few works in the literature actually provide demonstrations of truly distributed chemical sensing and, although there have been several attempts to realize these sensors (e.g. based on special fiber coatings), the vast majority of these attempts has failed to reach widespread use due to several reasons, among them: lack of sensitivity or selectivity, lack of range or resolution, cross sensitivity to temperature or strain, or need to work at specific wavelengths where fiber instrumentation becomes extremely expensive or unavailable. In this work we provide a preliminary demonstration of the possibility of achieving distributed detection of gas presence with spectroscopic selectivity, high spatial resolution, potential for long range measurements and feasibility of having most of the interrogator system working at conventional telecom wavelengths. For a full exploitation of this concept, new fibers (or more likely, fiber bundles) should be developed capable of guiding specific wavelengths in the IR (corresponding to gas absorption wavelengths) with good overlap with the analyte while also having a solid core with good transmission behavior at 1.55 µm, and good thermal coupling between the two guiding structures. Article begins on next page)

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Fundamentals of Optical Fiber Sensing Schemes Based on Coherent Optical Time Domain Reflectometry: Signal Model Under Static Fiber Conditions

Cited by 133 publications

References 33 publications

Phase-sensitive OTDR probe pulse shapes robust against modulation-instability fading

Phase-sensitive OTDR probe pulse shapes robust against modulation-instability fading

Random Quadrature Demodulation for Direct Detection Single-Pulse Rayleigh C-OTDR

Distributed photothermal spectroscopy in microstructured optical fibers: towards high-resolution mapping of gas presence over long distances

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