scholarly journals The Sensitivity Improvement Characterization of Distributed Strain Sensors Due to Weak Fiber Bragg Gratings

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6431
Author(s):  
Кonstantin V. Stepanov ◽  
Andrey A. Zhirnov ◽  
Аnton O. Chernutsky ◽  
Kirill I. Koshelev ◽  
Alexey B. Pnev ◽  
...  
Keyword(s):  
Rayleigh Scattering ◽  
Signal To Noise Ratio ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Optical Time Domain Reflectometer ◽  
Sensitivity Improvement ◽  
Phase Sensitive ◽  
Optical Time ◽  
Electrical Components

Weak fiber Bragg gratings (WFBGs) in a phase-sensitive optical time-domain reflectometer (phi-OTDR) sensor offer opportunities to significantly improve the signal-to-noise ratio (SNR) and sensitivity of the device. Here, we demonstrate the process of the signal and noise components’ formation in the device reflectograms for a Rayleigh scattering phi-OTDR and a WFBG-based OTDR. We theoretically calculated the increase in SNR when using the same optical and electrical components under the same external impacts for both setups. The obtained values are confirmed on experimental installations, demonstrating an improvement in the SNR by about 19 dB at frequencies of 20, 100, and 400 Hz. In this way, the minimum recorded impact (at the threshold SNR = 10) can be reduced from 100 nm per 20 m of fiber to less than 5 nm per 20 m of fiber sensor.

scholarly journals Pulse-Width Multiplexing ϕ-OTDR for Nuisance-Alarm Rate Reduction

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3509 ◽  
Author(s):  
Xiang Zhong ◽  
Xicheng Gao ◽  
Huaxia Deng ◽  
Shisong Zhao ◽  
Mengchao Ma ◽  
...  
Keyword(s):  
Pulse Width ◽  
Signal To Noise Ratio ◽  
Fusion Algorithm ◽  
Multisensor Data Fusion ◽  
Optical Time Domain Reflectometer ◽  
Light Pulses ◽  
Phase Sensitive ◽  
Evidential Theory ◽  
Vibrating Table ◽  
Optical Time

A pulse-width multiplexing method for reducing the nuisance-alarm rate of a phase-sensitive optical time-domain reflectometer ( ϕ -OTDR) is described. In this method, light pulses of different pulse-widths are injected into the sensing fiber; the data acquired at different pulse-widths are regarded as the outputs of different sensors; and these data are then processed by a multisensor data fusion algorithm. In laboratory tests with a sensing fiber on a vibrating table, the effects of pulse-width on the signal-to-noise ratio (SNR) of the ϕ -OTDR data are observed. Furthermore, by utilizing the SNR as the feature in a feature-layer algorithm based on Dempster–Shafer evidential theory, a four-pulse-width multiplexing ϕ -OTDR system is constructed, and the nuisance-alarm rate is reduced by about 70%. These experimental results show that the proposed method has great potential for perimeter protection, since the nuisance-alarm rate is significantly reduced by using a simple configuration.

Characterization of Fiber Bragg Gratings by Phase-Sensitive Optical Low-Coherence Reflectometry

2006 ◽  
Vol 55 (5) ◽  
pp. 1696-1703 ◽  
Author(s):  
A.-F. Obaton ◽  
C. Palavicini ◽  
Y. Jaouenjaouen ◽  
E. Kerrinckx ◽  
Y. Quiquempois ◽  
...  
Keyword(s):  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Low Coherence ◽  
Phase Sensitive ◽  
Optical Low Coherence Reflectometry

scholarly journals High SNR Φ-OTDR with Multi-Transverse Modes Heterodyne Matched-Filtering Technology

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7460
Author(s):  
Yifan Liu ◽  
Junqi Yang ◽  
Bingyan Wu ◽  
Bin Lu ◽  
Luwei Shuai ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Incident Light ◽  
Matched Filtering ◽  
Rayleigh Backscattering ◽  
Optical Time Domain Reflectometer ◽  
Transverse Modes ◽  
Seismic Detection ◽  
Phase Sensitive ◽  
Optical Time ◽  
First Time

Phase-sensitive optical time domain reflectometer (Φ-OTDR) has attracted attention in scientific research and industry because of its distributed dynamic linear response to external disturbances. However, the signal-to-noise ratio (SNR) of Φ-OTDR is still a limited factor by the weak Rayleigh Backscattering coefficient. Here, the multi-transverse modes heterodyne matched-filtering technology is proposed to improve the system SNR. The capture efficiency and nonlinear threshold are increased with multiple transverse modes in few-mode fibers; the incident light energy is permitted to be enlarged by a wider probe pulse by using heterodyne matched-filtering without spatial resolution being deteriorated. As far as we know, this is the first time that both multi-transverse modes integration method and digital heterodyne matched filtering method have been used to improve the SNR of Φ-OTDR simultaneously. Experimental results show that the noise floor is reduced by 11.4 dB, while the target signal is kept. We believe that this proposed method will help DAS find important applications in marine acoustic detection and seismic detection.

Extending the operation range of a phase-sensitive optical time-domain reflectometer by using fibre with chirped Bragg gratings

2020 ◽  
Vol 50 (5) ◽  
pp. 510-513
Author(s):  
D R Kharasov ◽  
D M Bengalskii ◽  
M Yu Vyatkin ◽  
O E Nanii ◽  
E A Fomiryakov ◽  
...  
Keyword(s):  
Time Domain ◽  
Bragg Gratings ◽  
Optical Time Domain Reflectometer ◽  
Phase Sensitive ◽  
Optical Time ◽  
Time Domain Reflectometer

Characterization of Optical Fibers Supporting OAM States using Fiber Bragg Gratings

CLEO: 2014 ◽  
2014 ◽  
Author(s):  
L. Wang ◽  
B. Ung ◽  
P. Vaity ◽  
L. A. Rusch ◽  
Y. Messaddeq ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings

scholarly journals Spectral characterization of differential group delay in uniform fiber Bragg gratings

2005 ◽  
Vol 13 (25) ◽  
pp. 9954 ◽  
Author(s):  
S. Bette ◽  
C. Caucheteur ◽  
M. Wuilpart ◽  
P. Mégret ◽  
R. Garcia-Olcina ◽  
...  
Keyword(s):  
Group Delay ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Spectral Characterization ◽  
Differential Group Delay ◽  
Differential Group

Characterization of Optical Fiber Bragg Gratings as Strain Sensors Considering Load Direction

2008 ◽  
Author(s):  
Michael C. Emmons ◽  
Sunny Karnani ◽  
K. P. Mohanchandra ◽  
Gregory P. Carman ◽  
Stefano Trono ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Strain Sensors ◽  
Great Promise ◽  
Fiber Direction ◽  
Load Direction ◽  
Isotropic Composite ◽  
Loading Direction

This study investigates the influence of lay-up and load direction on embedded optical fiber Bragg gratings (FBGs) used as strain sensors. FBGs have shown great promise for application to structural health monitoring with advantages of small size and cylindrical geometry readily allowing for embedment within fiber reinforced composites. Characterization of the embedded FBGs is necessary to develop a rugged and reliable strain sensor. This paper specifically explores the effects of loading direction on the FBG strain outputs. A well behaved baseline case is established with results for gratings loaded parallel to the optical fiber direction while embedded parallel to the adjacent structural fibers in a quasi-isotropic composite. Results and analysis are also presented for a case involving a composite fabricated with the optical and structural fibers parallel to each other but perpendicular to the loading direction. Extremely good results are obtained relating FBG strain measurements with that of surface mounted resistance strain gauges.

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