Detection-Localization-Identification of Vibrations Over Long Distance SSMF With Coherent $\Delta \phi$-OTDR

Awwad, Élie; Dorize, Christian; Guerrier, Sterenn; Renaudier, Jérémie

doi:10.1109/jlt.2020.2993167

Cited by 18 publications

(5 citation statements)

References 15 publications

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“…However, such enhancement, which can be of many decibels, has not materialized in practical deployments due to the effects of the limited coherence of the sources. This limitation, induced by the phase noise of the laser in OPC φ-OTDR sensors, has been previously reported in several works in the literature [5], [14], [15], [16]. Its modeling, however, has been rather limited.…”

Section: Introductionmentioning

confidence: 91%

Phase Noise Effects on Phase-Sensitive OTDR Sensors Using Optical Pulse Compression

Loayssa

Sagues

Eyal

2022

J. Lightwave Technol.

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We introduce a detailed theoretical, numerical, and experimental study of the effects of laser's phase noise on the performance of phase-sensitive optical time-domain reflectometry (φ-OTDR) sensors that use optical pulse compression (OPC). Pulse compression is a technique that can be used to improve the received signal amplitude by increasing the effective energy of the pulses that are launched into the fiber without degrading the spatial resolution of the measurements. Therefore, it is a valuable tool to extend the range of these sensors and mitigate fiber attenuation constraints. However, it has been observed that the limited coherence of the laser source has a degrading effect on the actual performance enhancement that this method can provide. Here, we derive a theoretical model that can be used to quantify this degradation for any type of OPC such as those based on either linear frequency modulation (LFM) pulses or perfect periodic autocorrelation (PPA) bipolar bit sequences. The model facilitates numerical estimation of the sensitivity of the φ-OTDR measurements. It also produces theoretical expressions for the mean and the variance of the phase-noise perturbed backscatter response. These results are validated via numerical simulations and experiments in φ-OTDR setups using LFM as well as PPA OPC. Furthermore, we demonstrate the use of the model to investigate the basic trade-offs involved in the design of OPC φ-OTDR systems.

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Section: Introductionmentioning

confidence: 91%

Phase Noise Effects on Phase-Sensitive OTDR Sensors Using Optical Pulse Compression

Loayssa

Sagues

Eyal

2022

J. Lightwave Technol.

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“…Laser phase noise here is modelled as a Wiener process of variance σ 2 = 2π∆νT S where ∆ν is the laser linewidth, T S is the sampling period. Although this does not perfectly match the physical reality, for which laser frequency noise increases in 1/ f d , d ≥ 1 [11], this enables to predict the general evolution of the error on phase estimation over distance [27]. The propagation medium is the fibre, the model of which is described in the previous section.…”

Section: Das System Modelmentioning

confidence: 99%

“…The MISO case is not displayed in Figure 4(b) since it is comparable to SIMO. As depicted in Figure 4(b), the general trend of the phase StDv over long distance is to grow exponentially with distance, with a slope depending on the laser linewidth ∆ν [19,27]. The value ∆ν = 75Hz is used in the simulations since it corresponds to the laser used in the experiments in next section [19].…”

Section: Simulations: Accuracy and False Alarmsmentioning

confidence: 99%

“…1We change the formalism for the round-trip Jones matrix with respect to the one we used in[19,27] to align with[26] which better describes the SOP evolution after a round-trip in an optical fibre for each particular realization of U forward (β, Θ, γ) (Indeed, if we are only interested in phase noise statistics averaged over several realizations of backscattered SOP, both models are statistically equivalent. However, for each particular realization, the new model better depicts the SOP evolution).…”

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confidence: 99%

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Introducing Coherent MIMO Sensing, a fading-resilient, polarization-independent approach to phase-OTDR

Guerrier,

Dorize,

Awwad

et al. 2020

Preprint

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Nowadays, long distance optical fibre transmission systems use polarization diversity multiplexed signals to enhance transmission performance. Distributed acoustic sensors (DAS) use the same propagation medium ie. single mode optical fibre, and aims at comparable targets such as covering the highest distance with the best signal quality. In the case of sensors, a noiseless transmission enables to monitor a large quantity of mechanical events along the fibre. This paper aims at extending the perspectives of DAS systems with regard to technology breakthroughs introduced in long haul transmission systems over the last decade. We recently developed a sensor interrogation method based on coherent phase-sensitive optical time domain reflectometry (φ-OTDR), with dual polarization multiplexing at the transmitter and polarization diversity at the receiver. We name this technique Coherent-MIMO sensing. A study is performed from a dual-polarization numerical model to compare several sensor interrogation techniques, including Coherent-MIMO. We demonstrate that dual-polarization probing of a fibre sensor makes it insensitive to polarization effects, decreases the risks of false alarms and thus strongly enhances its sensitivity. The simulations results are validated with an experiment, and finally quantitative data are given on the performance increase enabled by Coherent-MIMO sensing.

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“…The SNR improvement brought by OPC is, in principle, proportional to the increased duration (energy) of the compression waveform compared to the use of a simple pulse. However, early on, it was found that OPC performance was constrained by the phase noise of the laser source [13], [15], [16]. We have recently studied this effect in detail developing a theoretical model and finding that the sensitivity of OPC-COTDR degrades due to phase noise as the pulse duration is increased [17].…”

Section: Introductionmentioning

confidence: 99%

Compensation of Phase Noise Impairments in Distributed Acoustic Sensors Based on Optical Pulse Compression Time-Domain Reflectometry

PiAeiro

Sagues

Loayssa

2023

J. Lightwave Technol.

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We introduce a method to compensate for the deleterious effects of the phase noise of the laser source on long-range distributed acoustic sensors (DAS) that implement optical pulse compression (OPC). Pulse compression can be used in coherent optical time-domain reflectometry (COTDR) sensors to extend the measurement range without compromising spatial resolution. In fact, OPC-COTDR sensors have demonstrated the longest measurement range to date in passive sensing links that do not require distributed amplification to compensate fiber attenuation. However, it has been found that the limited coherence of the laser source has a degrading effect on the actual performance enhancement that pulse compression can bring because it constrains the maximum duration of the compression waveforms that can be used and makes the use of lasers with extremely low phase noise necessary. We introduce a technique to compensate for the effects of phase noise on OPC-COTDR sensors so that they can demonstrate their full potential for long-range measurements using lasers with less stringent phase noise requirements. The method is based on sampling the phase noise of the laser with an auxiliary interferometer and using this information in a simple signal processing technique to mitigate its deleterious effect on the signal measured. We test our method in an OPC-COTDR sensor that uses 500-µs linear frequency modulated pulses to demonstrate 100-km range measurements with 200 p / √ Hz of strain sensitivity at 2-m initial spatial resolution that becomes 10-m after applying the gauge length. To our knowledge, this is the longest compression waveform demonstrated to date in an OPC-COTDR sensor. Its use provides an extra 20-km range compared to previous demonstrations using laser sources of comparable linewidth. Furthermore, comparable performance is also demonstrated when using a laser source with an order of magnitude larger linewidth.

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Detection-Localization-Identification of Vibrations Over Long Distance SSMF With Coherent $\Delta \phi$-OTDR

Cited by 18 publications

References 15 publications

Phase Noise Effects on Phase-Sensitive OTDR Sensors Using Optical Pulse Compression

Phase Noise Effects on Phase-Sensitive OTDR Sensors Using Optical Pulse Compression

Introducing Coherent MIMO Sensing, a fading-resilient, polarization-independent approach to phase-OTDR

Compensation of Phase Noise Impairments in Distributed Acoustic Sensors Based on Optical Pulse Compression Time-Domain Reflectometry

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