Abstract Distributed optical fibre sensors deliver a map of physical quantity along an fibre, providing unique solution for health monitoring targeted structures. Considerable developments over recent years have pushed conventional distributed towards their ultimate performance, while any significant improvement demands substantial hardware overhead. Here, technique is proposed, encoding the interrogating light signal by single-sequence aperiodic code and spatially resolving information...

Download This Paper Open PDF in Browser Add to My Library Share: Permalink Using these links will ensure access this page indefinitely Copy URL DOI

The signal-to-noise ratio (SNR) of Brillouin optical time-domain analyzers (BOTDA) is modelled and experimentally validated, using direct detection with without the use pre-amplification. behavior SNR as a function gain probe power reaching photo analyzed in depth this developed model checked two photodetectors different specifications. It proves that pre-amplification associated to good-quality photodetector well-matched post-processing filtering can secure highest for direct-detection...

A novel, to the best of our knowledge, postprocessing technique is proposed extract with a flexible and variable spatial resolution information from Brillouin optical time-domain analyzers, obtained using pulse longer than acoustic settling time. The negative impact transient effect suppressed, enabling response proportional gain spectrum keeping its natural linewidth. This leads better overall sensing performance, in particular for submetric resolutions, no compromises on range measurement

Noise models for both single-pulse and coded Brillouin optical time-domain analyzers (BOTDA) are established to quantify the actual signal-to-noise ratio (SNR) enhancement provided by pulse coding at any fiber position in operating condition. Simulation experimental results show that polarization noise spontaneous scattering (SpBS) signal beating could highly penalize performance of coded-BOTDA, depending on code type interrogated position. The also serve as a useful tool optimize SNR...

The tolerance of the non-local effect in BOTDA method using a dual-tone probe wave with fixed frequency separation is theoretically and experimentally investigated this paper. presented analysis points out that when sensing fiber consists two long segments large BFS difference (> 100 MHz), there will always be only one tone interacting pump pulse front segment. Therefore, although distortion problem can still overcome case, conventional would impose systematic error on estimated hotspot...

This paper proposes a novel method based on differential π-phase-shift long-pulse-width pair to narrow the Brillouin gain spectrum for improving frequency accuracy in optical time-domain analysis (BOTDA) system. is first approach reduce bandwidth of distributed sensing best our knowledge. The temporal and spectral responses proposal are analytically solved, key parameters such as pulse width length section investigated. Theoretical experimental results demonstrate that could achieve 17 MHz...

Brillouin optical time-domain reflectometry is used to perform distributed forward stimulated scattering (FSBS) measurements. This configuration suppresses the need for an additional frequency scanning evaluate local peak gain when probing FSBS resonance. The use of a broad pass-band filter makes system insensitive moderate temperature or strain fluctuations, but enables accurately retrieve any change in intensity due FSBS.

Abstract The health monitoring of superconducting fault current limiters (SFCL) is important for their large-scale exploitation in HVDC grids protection. intrinsic non-homogeneity critical along the superconductor length can cause localized points heating, called hotspots, SFCL device which lead to damage. In this paper we propose use an extremely simple and cost-effective technique based on all-fibre Mach-Zehnder interferometers hotspot detection SFCLs, where measurement arm interferometer...

When studying the spatial resolution and Brillouin frequency shift (BFS) uncertainty in optical time domain analysis (BOTDA) system with a hotspot, people usually focuses on point best performance hotspot neglect huge error around it. The is caused by gain spectrum (BGS) contributed both ambient segment, which distorted from standard Lorentzian curve. Due to distortion of BGS, estimated BFS near shifted actual value results along fiber. BGS can be double-peak or single-peak curve that...

Wavelength division multiplexing (WDM) is an important technique for next-generation networks, which offers a viable solution to fully exploit the enormous bandwidth available in fiber optics. Optical layer multicast refers support of point-to-multipoint connections directly at physical by employing passive devices known as power splitters. Since requirement individual user only fraction optical channel capacity, problem traffic grooming crucial constituent designing WDM networks. This paper...

The robustness of a recently proposed Brillouin optical time-domain analysis sensor based on dual-tone probe wave with fixed frequency separation is deeply studied. It discovered that when the distribution shift (BFS) along sensing fiber not entirely uniform, non-local effect might be imposed at middle fiber, which gives rise to systematic error local estimated BFS. Aiming solving this problem, we propose an approach acquires both upper and lower sidebands simultaneously using two...

An adaptive decoder is proposed to derive the fiber single-pulse response. This experimentally simple technique simultaneously improves measurement time and noise level, boosting an uncommon degree overall performance of distributed sensors.

The robustness of the BOTDA method based on dual-tone probe wave with fixed frequency separation is studied. It verified that when sensing fiber consists two segments large Brillouin shift difference (>100 MHz), non-local effect would take place in front segment, which gives rise to error determination hotspot. Aiming at solving this problem, both upper and lower sidebands are acquired simultaneously by using photodiodes, average between gain loss spectrum calculated eliminate detrimental...

The rheological stress recovery (RSR) method was proposed to obtain measurements of in-situ stress. Rock can be evaluated by monitoring the process sensors embedded in rock mass. In order achieve this application, a novel sensor employing fiber Bragg grating (FBG) technique designed and manufactured. This consisted three parts: A sensing spherical head, connecting rod, coupler box. six independent pressure units were assembled together with temperature compensation unit. addition, wavelength...

To solve the problem of low demodulation accuracy conventional peak-to-peak algorithm for fiber-optic Fabry-Perot (FP) sensors due to failure determining interference order, a novel cavity length sequence matching based on combined valley peak positioning is proposed. Firstly, pair and its neighboring in reflection spectrum selected positioned, two groups orders are supposed generate sequences. Finally, these lengths compared find real order extraction accurate length. In verify feasibility...

A high-performance Brillouin optical time-domain analysis (BOTDA) is achieved using the gain bandwidth reduction technique combined with high injected probe power. In branch, dual-tone wave fixed frequency separation used for enhancing power to +5 dBm. pump a differential π-phase-shift long-pulse width pair narrow spectrum. On basis of and 2.5-m spatial resolution, spectrum can be narrowed level 17 MHz, whereas conventional single-pulse BOTDA sensor 51 MHz. As result, 50-km sensing range...

A Brillouin optical time-domain analysis (BOTDA) technique for enhancing the probe power to +5 dBm is proposed and demonstrated, which based on a conventional dual sideband setup, but waves are modulated by frequency shift keying signal. The pump distortion compensated in time domain with this technique. By employing 105-km sensing fiber, experimentally validated 2-m spatial resolution. Furthermore, another experiment designed show good tolerance fibers combined large (BFS) difference, as...

A large number of patents have been recently devoted to the development rapid molding technology using metal arc spraying with high-melting-point and high-hardness metals (carbon alloy steels). Manufacturing arcspraying dye is attractive because not only material relatively cheap but shell also has properties high hardness strength that greatly improves service life dye. The application scope thus expanded provide better forming precision for manufacture industry. Among these a highmelting-...

Identified and detailed time-series model according to transport volume impact factor combined with ACF, PACF Legend, estimated parameter diagnosed by logistic regression ARIMA technology. The results showed that 1 is not sensitive external factors while 2 is, the best one.

Get PDF Email Share with Facebook Tweet This Post on reddit LinkedIn Add to CiteULike Mendeley BibSonomy Citation Copy Text S. Wang, X. Hong, Sun, and J. Wu, "Brillouin optical time domain analyzer FSK probe wave," in Asia Communications Photonics Conference, OSA Technical Digest (online) (Optica Publishing Group, 2017), paper Su1L.6. Export BibTex Endnote (RIS) HTML Plain alert Save article

A novel interpolation algorithm of cross-correlation method is proposed for estimating the BFS in BOTDA sensors. Based on this technique, higher frequency accuracy and shorter time are realized.