The Experts below are selected from a list of 16011 Experts worldwide ranked by ideXlab platform

Luc Thevenaz - One of the best experts on this subject based on the ideXlab platform.

  • rayleigh based distributed Optical Fiber Sensing using least mean square similarity
    26th International Conference on Optical Fiber Sensors (2018) paper ThE29, 2018
    Co-Authors: Li Zhang, Marcelo A Soto, Zhisheng Yang, Flavien Gyger, Luc Thevenaz
    Abstract:

    A highly sensitive distributed pressure Sensing system (< 20 hPa) based on phase sensitive Optical time-domain reflectometry with side air holes Fiber is proposed, reaching a Sensing range of 1.05 km with a 5 cm spatial resolution.

  • temperature strain discrimination in distributed Optical Fiber Sensing using phase sensitive Optical time domain reflectometry
    Optics Express, 2017
    Co-Authors: Xin Lu, Marcelo A Soto, Luc Thevenaz
    Abstract:

    A method based on coherent Rayleigh scattering distinctly evaluating temperature and strain is proposed and experimentally demonstrated for distributed Optical Fiber Sensing. Combining conventional phase-sensitive Optical time-domain domain reflectometry (ϕOTDR) and ϕOTDR-based birefringence measurements, independent distributed temperature and strain profiles are obtained along a polarization-maintaining Fiber. A theoretical analysis, supported by experimental data, indicates that the proposed system for temperature-strain discrimination is intrinsically better conditioned than an equivalent existing approach that combines classical Brillouin Sensing with Brillouin dynamic gratings. This is due to the higher sensitivity of coherent Rayleigh scatting compared to Brillouin scattering, thus offering better performance and lower temperature-strain uncertainties in the discrimination. Compared to the Brillouin-based approach, the ϕOTDR-based system here proposed requires access to only one Fiber-end, and a much simpler experimental layout. Experimental results validate the full discrimination of temperature and strain along a 100 m-long elliptical-core polarization-maintaining Fiber with measurement uncertainties of ~40 mK and ~0.5 μe, respectively. These values agree very well with the theoretically expected measurand resolutions.

  • distributed phase birefringence measurements based on polarization correlation in phase sensitive Optical time domain reflectometers
    Optics Express, 2015
    Co-Authors: Marcelo A Soto, Xin Lu, Hugo F Martins, Miguel Gonzalezherraez, Luc Thevenaz
    Abstract:

    In this paper a technique to measure the distributed birefringence profile along Optical Fibers is proposed and experimentally validated. The method is based on the spectral correlation between two sets of orthogonally-polarized measurements acquired using a phase-sensitive Optical time-domain reflectometer (ϕOTDR). The correlation between the two measured spectra gives a resonance (correlation) peak at a frequency detuning that is proportional to the local refractive index difference between the two orthogonal polarization axes of the Fiber. In this way the method enables local phase birefringence measurements at any position along Optical Fibers, so that any longitudinal fluctuation can be precisely evaluated with metric spatial resolution. The method has been experimentally validated by measuring Fibers with low and high birefringence, such as standard single-mode Fibers as well as conventional polarization-maintaining Fibers. The technique has potential applications in the characterization of Optical Fibers for telecommunications as well as in distributed Optical Fiber Sensing.

  • design of simulator for seepage detection in an embankment based on distributed optic fibre Sensing technology
    Chinese Journal of Scientific Instrument, 2007
    Co-Authors: Pingyu Zhu, Luc Thevenaz, Yuanbao Leng, Yang Zhou
    Abstract:

    Based on the temperature change in an embankment, a seepage flow simulator and monitoring system based on distributed Optical Fiber Sensing are proposed. A simulator is designed that consists of scale model of embankment with definite length, seepage flow control cell and monitoring cell. Conventional hygrothermograph and flowmeter are employed in system dispersedly. The results from those conventional instruments were used to compare with the data from a distributed fibre Sensing DiTeSt analyzer. The simulator equipment can monitor various embankments with different boundary conditions, such as temperature, distributions of soakage line and scales. The process of producing seepage pathway and configuration of Sensing cable are presented, as well as test results with a field-installed Fiber optic Sensing cable. The simulator and results are helpful to build reasonable configurations for field real-time monitoring of abnormal seepage flow, which also offer an effective approach to study problems related to a secured embankment.

Marcelo A Soto - One of the best experts on this subject based on the ideXlab platform.

  • rayleigh based distributed Optical Fiber Sensing using least mean square similarity
    26th International Conference on Optical Fiber Sensors (2018) paper ThE29, 2018
    Co-Authors: Li Zhang, Marcelo A Soto, Zhisheng Yang, Flavien Gyger, Luc Thevenaz
    Abstract:

    A highly sensitive distributed pressure Sensing system (< 20 hPa) based on phase sensitive Optical time-domain reflectometry with side air holes Fiber is proposed, reaching a Sensing range of 1.05 km with a 5 cm spatial resolution.

  • temperature strain discrimination in distributed Optical Fiber Sensing using phase sensitive Optical time domain reflectometry
    Optics Express, 2017
    Co-Authors: Xin Lu, Marcelo A Soto, Luc Thevenaz
    Abstract:

    A method based on coherent Rayleigh scattering distinctly evaluating temperature and strain is proposed and experimentally demonstrated for distributed Optical Fiber Sensing. Combining conventional phase-sensitive Optical time-domain domain reflectometry (ϕOTDR) and ϕOTDR-based birefringence measurements, independent distributed temperature and strain profiles are obtained along a polarization-maintaining Fiber. A theoretical analysis, supported by experimental data, indicates that the proposed system for temperature-strain discrimination is intrinsically better conditioned than an equivalent existing approach that combines classical Brillouin Sensing with Brillouin dynamic gratings. This is due to the higher sensitivity of coherent Rayleigh scatting compared to Brillouin scattering, thus offering better performance and lower temperature-strain uncertainties in the discrimination. Compared to the Brillouin-based approach, the ϕOTDR-based system here proposed requires access to only one Fiber-end, and a much simpler experimental layout. Experimental results validate the full discrimination of temperature and strain along a 100 m-long elliptical-core polarization-maintaining Fiber with measurement uncertainties of ~40 mK and ~0.5 μe, respectively. These values agree very well with the theoretically expected measurand resolutions.

  • distributed phase birefringence measurements based on polarization correlation in phase sensitive Optical time domain reflectometers
    Optics Express, 2015
    Co-Authors: Marcelo A Soto, Xin Lu, Hugo F Martins, Miguel Gonzalezherraez, Luc Thevenaz
    Abstract:

    In this paper a technique to measure the distributed birefringence profile along Optical Fibers is proposed and experimentally validated. The method is based on the spectral correlation between two sets of orthogonally-polarized measurements acquired using a phase-sensitive Optical time-domain reflectometer (ϕOTDR). The correlation between the two measured spectra gives a resonance (correlation) peak at a frequency detuning that is proportional to the local refractive index difference between the two orthogonal polarization axes of the Fiber. In this way the method enables local phase birefringence measurements at any position along Optical Fibers, so that any longitudinal fluctuation can be precisely evaluated with metric spatial resolution. The method has been experimentally validated by measuring Fibers with low and high birefringence, such as standard single-mode Fibers as well as conventional polarization-maintaining Fibers. The technique has potential applications in the characterization of Optical Fibers for telecommunications as well as in distributed Optical Fiber Sensing.

  • optimization of a dpp botda sensor with 25 cm spatial resolution over 60 km standard single mode Fiber using simplex codes and Optical pre amplification
    Optics Express, 2012
    Co-Authors: Marcelo A Soto, Mohammad Taki, G Bolognini, Fabrizio Di Pasquale
    Abstract:

    Sub-meter distributed Optical Fiber Sensing based on Brillouin Optical time-domain analysis with differential pulse-width pairs (DPP-BOTDA) is combined with the use of Optical pre-amplification and pulse coding. In order to provide significant measurement SNR enhancement and to avoid distortions in the Brillouin gain spectrum due to acoustic-wave pre-excitation, the pulse width and duty cycle of Simplex coding based on return-to-zero pulses are optimized through simulations. In addition, the use of linear Optical pre-amplification increases the receiver sensitivity and the overall dynamic range of DPP-BOTDA measurements. Experimental results demonstrate for first time a spatial resolution of ~25 cm over a 60 km standard single-mode Fiber (equivalent to ~240k discrete Sensing points) with temperature resolution of 1.2°C and strain resolution of 24 μe.

Vincent Lamour - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic Optical Fiber Sensing With Brillouin Optical Time Domain Reflectometry: Application to Pipeline Vibration Monitoring
    Journal of Lightwave Technology, 2017
    Co-Authors: Damien Maraval, Renaud Gabet, Yves Jaouen, Vincent Lamour
    Abstract:

    Brillouin distributed Optical Fiber strain sensors are often limited to static events because of necessary long acquisition time due to the frequency sweep technique. Dynamic distributed strain monitoring is necessary to ensure the integrity of linear structures submitted to fatigue loading or vibrations, such as subsea risers or flowlines, overhead pipelines, long bridges, railways, or high-rise towers. In this paper, a novel dynamic Brillouin Optical time domain reflectometer for single ended truly distributed strain measurement based on the slope-assisted method is presented. The Optical local oscillator frequency is adjusted to measure Brillouin backscattered power at the maximum slope of the Brillouin gain spectrum along the Fiber length. Any strain variation inducing Brillouin frequency shift will be detected by amplitude variation. To demonstrate the performance of our acquisition system, three Optical Fibers have been implemented along a 10 m steel pipe submitted to vibration. Through this mockup testing, we were able to measure the oscillation damping time and the geometrical displacement of the pipe in real time. A 7.6 Hz acquisition rate was achieved with a strain error of ± 40 μ strain and with a spatial resolution of 1 m. From integration of longitudinal strains, pipe displacement is calculated with an error of ± 12 mm. A performance comparison between frequency sweep and slope assisted method is made with a 2 km Fiber sensor.

  • smart sleeper measurement of bending moments in concrete sleepers laid on ballast tracks
    Transport Research Arena (TRA) 5th Conference: Transport Solutions from Research to DeploymentEuropean CommissionConference of European Directors of R, 2014
    Co-Authors: Arnaud Loaec, Charles Petit, Vincent Lanticq, Vincent Lamour
    Abstract:

    “Smart Sleeper” is a surveillance tool allowing long term monitoring of the track through strain measurement of the concrete sleeper. The embedded Optical Fiber Sensing technology used for strain measurement is chosen for its high performance static and dynamic properties and for its electromagnetic immunity. “Smart Sleeper” can therefore be used as a durable tool to characterize the in situ track mechanical behavior under dynamic loading. Through Smart Sleeper, condition monitoring may also be performed to optimize track predictive maintenance.

Xin Lu - One of the best experts on this subject based on the ideXlab platform.

  • temperature strain discrimination in distributed Optical Fiber Sensing using phase sensitive Optical time domain reflectometry
    Optics Express, 2017
    Co-Authors: Xin Lu, Marcelo A Soto, Luc Thevenaz
    Abstract:

    A method based on coherent Rayleigh scattering distinctly evaluating temperature and strain is proposed and experimentally demonstrated for distributed Optical Fiber Sensing. Combining conventional phase-sensitive Optical time-domain domain reflectometry (ϕOTDR) and ϕOTDR-based birefringence measurements, independent distributed temperature and strain profiles are obtained along a polarization-maintaining Fiber. A theoretical analysis, supported by experimental data, indicates that the proposed system for temperature-strain discrimination is intrinsically better conditioned than an equivalent existing approach that combines classical Brillouin Sensing with Brillouin dynamic gratings. This is due to the higher sensitivity of coherent Rayleigh scatting compared to Brillouin scattering, thus offering better performance and lower temperature-strain uncertainties in the discrimination. Compared to the Brillouin-based approach, the ϕOTDR-based system here proposed requires access to only one Fiber-end, and a much simpler experimental layout. Experimental results validate the full discrimination of temperature and strain along a 100 m-long elliptical-core polarization-maintaining Fiber with measurement uncertainties of ~40 mK and ~0.5 μe, respectively. These values agree very well with the theoretically expected measurand resolutions.

  • distributed phase birefringence measurements based on polarization correlation in phase sensitive Optical time domain reflectometers
    Optics Express, 2015
    Co-Authors: Marcelo A Soto, Xin Lu, Hugo F Martins, Miguel Gonzalezherraez, Luc Thevenaz
    Abstract:

    In this paper a technique to measure the distributed birefringence profile along Optical Fibers is proposed and experimentally validated. The method is based on the spectral correlation between two sets of orthogonally-polarized measurements acquired using a phase-sensitive Optical time-domain reflectometer (ϕOTDR). The correlation between the two measured spectra gives a resonance (correlation) peak at a frequency detuning that is proportional to the local refractive index difference between the two orthogonal polarization axes of the Fiber. In this way the method enables local phase birefringence measurements at any position along Optical Fibers, so that any longitudinal fluctuation can be precisely evaluated with metric spatial resolution. The method has been experimentally validated by measuring Fibers with low and high birefringence, such as standard single-mode Fibers as well as conventional polarization-maintaining Fibers. The technique has potential applications in the characterization of Optical Fibers for telecommunications as well as in distributed Optical Fiber Sensing.

Yongkang Dong - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic Distributed Brillouin Optical Fiber Sensing Based on Dual-Modulation by Combining Single Frequency Modulation and Frequency-Agility Modulation
    IEEE Photonics Journal, 2017
    Co-Authors: Dexin Ba, Zhiwei Lu, Dengwang Zhou, Yongkang Dong, Benzhang Wang, Zhigang Fan, Hui Li
    Abstract:

    © 2017 IEEE. Dynamic Brillouin Optical Fiber sensors based on fast scanning of Brillouin gain spectrum (BGS) are one of the most promising techniques to measure dynamic strains, where an 11-GHz bandwidth arbitrary waveform generator (AWG) or a vector microwave generator is essential for frequency agility. A dynamic Brillouin Optical Fiber sensor based on dual-modulation is proposed here, which aims to realize dynamic Sensing via a lowbandwidth AWG. In this protocol, the scanning of BGS is implemented by the combination of a single-frequency modulation and a frequency-Agility modulation. The frequency of the single-frequency modulation is slightly lower than the Brillouin frequency shift of the Fiber under test so that the tuning range of the frequency-Agility modulation is required to cover only several-hundred MHz for the scanning of the BGS, which significantly reduces the bandwidth requirement for the AWG. In experiment, an 11.8-Hz strain is measured with a 30-m Fiber, where the spatial resolution and the sampling rate are 1 m and 200 Hz, respectively. Furthermore, by tracking the damping vibration of the Optical Fiber, its resonant frequency is measured with a sampling rate of 100 Hz.

  • distributed measurement of dynamic strain based on multi slope assisted fast botda
    Optics Express, 2016
    Co-Authors: Benzhang Wang, Dengwang Zhou, Yongkang Dong, Mingjing Yin, Zhigang Fan
    Abstract:

    We propose and demonstrate a dynamic Brillouin Optical Fiber Sensing based on the multi-slope assisted fast Brillouin Optical time-domain analysis (F-BOTDA), which enables the measurement of a large strain with real-time data processing. The multi-slope assisted F-BOTDA is realized based on the double-slope demodulation and frequency-agile modulation, which significantly increases the measurement range compared with the single- or double- slope assisted F-BOTDA, while maintaining the advantage of fast data processing and being suitable for real-time on-line monitoring. A maximum strain variation up to 5000μe is measured in a 32-m Fiber with a spatial resolution of ~1m and a sampling rate of 1kHz. The frequency of the strain is 12.8Hz, which is limited by the rotation rate of the motor used to load the force on the Fiber. Furthermore, the influence of the frequency difference between two adjacent probe tones on the measurement error is studied theoretically and experimentally for optimization. For a Brillouin gain spectrum with a 78-MHz width, the optimum frequency difference is ~40MHz. The measurement error of Brillouin frequency shift is less than 3MHz over the whole measurement range (241MHz).

  • Bend-insensitive distributed Sensing in singlemode-multimode-singlemode Optical Fiber structure by using Brillouin Optical time-domain analysis
    Optics Express, 2015
    Co-Authors: Yongkang Dong, Juwang Zhang, Xiaoyi Bao, Taofei Jiang, Pengbai Xu, Zhiwei Lu, Jinlong Xu, Dengwang Zhou, Tao Zhu, Hongying Zhang
    Abstract:

    We propose a bend-insensitive distributed Brillouin Optical Fiber Sensing by using a singlemode-multimode-singlemode Optical Fiber structure for the first time to the best of our knowledge. The Sensing Fiber is a graded-index multimode Fiber (GI-MMF) sandwiched by two standard single-mode Fibers (SMFs) with central-alignment splicing at the interface between GI-MMF and SMF to excite the fundamental mode in GI-MMF. The Sensing system can resist a minimal bend radius of 1.25mm while maintain the measurement performance, with which the measured coefficients of strain and temperature are 421.6MHz/% and 0.826MHz/°C, respectively. We also demonstrate that the higher-order modes excited in GI-MMF can be easily influenced by bending, so that exciting the fundamental mode is essential for bend-insensitive distributed Sensing.