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Agile Technique
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Yongkang Dong – One of the best experts on this subject based on the ideXlab platform.
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Fast Brillouin Optical Time-Domain Reflectometry Based on the Frequency-Agile Technique
Journal of Lightwave Technology, 2020Co-Authors: Benzhang Wang, Dengwang Zhou, Chao Pang, Zijie Hua, Dianyang Lin, Yongkang DongAbstract:A fast Brillouin optical time-domain reflectometry (BOTDR) for dynamic strain measurement is proposed and experimentally demonstrated based on the frequency-Agile Technique. Employing the band-pass filter and envelope detection, the spontaneous Brillouin gain spectrum can be online demodulated in the time domain for a truly distributed, one-end-access and dynamic strain measurement. A strain sampling rate of 62.5 Hz is achieved for the proposed sensor over 172 m single-mode fiber with 100 sweeping frequencies and 64 times of averaging. In the experiment, the vibration frequencies of 6.82 Hz and 14.77 Hz have been measured with 2 m spatial resolution and 4000 μϵ dynamic range. The measurement accuracy is calculated to be ±30 μϵ by the standard deviation of the static fiber Brillouin frequency shift. Furthermore, the performance on the strain sampling rate and measurement accuracy is investigated with different averaging times. It should be noted that the upgraded schemes for the frequency-Agile based Brillouin optical time-domain analysis can be also introduced into the proposed fast BOTDR.
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Ultra-fast distributed Brillouin optical fiber sensing for dynamic strain measurement
International Photonics and OptoElectronics Meeting 2019 (OFDA OEDI ISST PE LST TSA), 2019Co-Authors: Yongkang DongAbstract:The key operation of traditional Brillouin optical time-domain analysis (BOTDA) is the frequency-sweeping process to get the distributed Brillouin gain spectrum (BGS) whose central frequency (i.e. Brillouin frequency shift, BFS) has a linear relationship with the environmental information (e.g. temperature or strain) over the sensing fiber. However, this time-consuming process has limited the sampling rate of BOTDA. In this paper, we summarize several fast BOTDA systems for dynamic strain measurement which is developed by our team and refers to frequency-Agile Technique, slope-assisted methods and optical chirp chain Technique.
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single shot botda based on an optical chirp chain probe wave for distributed ultrafast measurement
Light-Science & Applications, 2018Co-Authors: Dengwang Zhou, Yongkang Dong, Enzhang Wang, Chao Pang, Dexi A, Hongying ZhangAbstract:Brillouin optical time-domain analysis (BOTDA) requires frequency mapping of the Brillouin spectrum to obtain environmental information (e.g., temperature or strain) over the length of the sensing fiber, with the finite frequency-sweeping time-limiting applications to only static or slowly varying strain or temperature environments. To solve this problem, we propose the use of an optical chirp chain probe wave to remove the requirement of frequency sweeping for the Brillouin spectrum, which enables distributed ultrafast strain measurement with a single pump pulse. The optical chirp chain is generated using a frequency-Agile Technique via a fast-frequency-changing microwave, which covers a larger frequency range around the Stokes frequency relative to the pump wave, so that a distributed Brillouin gain spectrum along the fiber is realized. Dynamic strain measurements for periodic mechanical vibration, mechanical shock, and a switch event are demonstrated at sampling rates of 25 kHz, 2.5 MHz and 6.25 MHz, respectively. To the best of our knowledge, this is the first demonstration of distributed Brillouin strain sensing with a wide-dynamic range at a sampling rate of up to the MHz level.
Hongying Zhang – One of the best experts on this subject based on the ideXlab platform.
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single shot botda based on an optical chirp chain probe wave for distributed ultrafast measurement
Light-Science & Applications, 2018Co-Authors: Dengwang Zhou, Yongkang Dong, Enzhang Wang, Chao Pang, Dexi A, Hongying ZhangAbstract:Brillouin optical time-domain analysis (BOTDA) requires frequency mapping of the Brillouin spectrum to obtain environmental information (e.g., temperature or strain) over the length of the sensing fiber, with the finite frequency-sweeping time-limiting applications to only static or slowly varying strain or temperature environments. To solve this problem, we propose the use of an optical chirp chain probe wave to remove the requirement of frequency sweeping for the Brillouin spectrum, which enables distributed ultrafast strain measurement with a single pump pulse. The optical chirp chain is generated using a frequency-Agile Technique via a fast-frequency-changing microwave, which covers a larger frequency range around the Stokes frequency relative to the pump wave, so that a distributed Brillouin gain spectrum along the fiber is realized. Dynamic strain measurements for periodic mechanical vibration, mechanical shock, and a switch event are demonstrated at sampling rates of 25 kHz, 2.5 MHz and 6.25 MHz, respectively. To the best of our knowledge, this is the first demonstration of distributed Brillouin strain sensing with a wide-dynamic range at a sampling rate of up to the MHz level.
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Wide-range dynamic strain measurements based on K-BOTDA and frequency-Agile Technique
25th International Conference on Optical Fiber Sensors, 2017Co-Authors: Dengwang Zhou, Yongkang Dong, Benzhang Wang, Hongying ZhangAbstract:We propose and demonstrate a novel fast Brillouin optical time-domain analysis system using the coefficient K spectrum which is defined as the ratio of phase-shift and gain of Brillouin amplification, where K features linear response, immune to the variation of pump power and a wide measure range. For a 30ns-square pump pulse, the frequency span of K spectrum can reach up to 200MHz. In dynamic strain experiment, a multi-slope assisted K-BOTDA with the measured strain of 5358.3μe and the vibration frequency of 6.01Hz and 12.05Hz are demonstrated.
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Slope-assisted BOTDA based on vector SBS and frequency-Agile Technique for wide-strain-range dynamic measurements.
Optics express, 2017Co-Authors: Dengwang Zhou, Yongkang Dong, Benzhang Wang, Taofei Jiang, Hongying ZhangAbstract:We present a slope-assisted BOTDA system based on the vector stimulated Brillouin scattering (SBS) and frequency-Agile Technique (FAT) for the wide-strain-range dynamic measurement. A dimensionless coefficient K defined as the ratio of Brillouin phase-shift to gain is employed to demodulate the strain of the fiber, and it is immune to the power fluctuation of pump pulse and has a linear relation of the frequency detuning for the continuous pump and Stokes waves. For a 30ns-square pump pulse, the available frequency span of the K spectrum can reach up to 200MHz, which is larger than fourfold of 48MHz-linewidth of Brillouin gain spectrum. For a single-slope assisted BOTDA, dynamic strain measurement with the maximum strain of 2467.4μe and the vibration frequency components of 10.44Hz and 20.94Hz is obtained. For a multi-slope-assisted BOTDA, dynamic measurement with the strain variation up to 5372.9μe and the vibration frequency components of 5.58Hz and 11.14Hz is achieved by using FAT to extend the strain range.
Dengwang Zhou – One of the best experts on this subject based on the ideXlab platform.
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Fast Brillouin Optical Time-Domain Reflectometry Based on the Frequency-Agile Technique
Journal of Lightwave Technology, 2020Co-Authors: Benzhang Wang, Dengwang Zhou, Chao Pang, Zijie Hua, Dianyang Lin, Yongkang DongAbstract:A fast Brillouin optical time-domain reflectometry (BOTDR) for dynamic strain measurement is proposed and experimentally demonstrated based on the frequency-Agile Technique. Employing the band-pass filter and envelope detection, the spontaneous Brillouin gain spectrum can be online demodulated in the time domain for a truly distributed, one-end-access and dynamic strain measurement. A strain sampling rate of 62.5 Hz is achieved for the proposed sensor over 172 m single-mode fiber with 100 sweeping frequencies and 64 times of averaging. In the experiment, the vibration frequencies of 6.82 Hz and 14.77 Hz have been measured with 2 m spatial resolution and 4000 μϵ dynamic range. The measurement accuracy is calculated to be ±30 μϵ by the standard deviation of the static fiber Brillouin frequency shift. Furthermore, the performance on the strain sampling rate and measurement accuracy is investigated with different averaging times. It should be noted that the upgraded schemes for the frequency-Agile based Brillouin optical time-domain analysis can be also introduced into the proposed fast BOTDR.
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single shot botda based on an optical chirp chain probe wave for distributed ultrafast measurement
Light-Science & Applications, 2018Co-Authors: Dengwang Zhou, Yongkang Dong, Enzhang Wang, Chao Pang, Dexi A, Hongying ZhangAbstract:Brillouin optical time-domain analysis (BOTDA) requires frequency mapping of the Brillouin spectrum to obtain environmental information (e.g., temperature or strain) over the length of the sensing fiber, with the finite frequency-sweeping time-limiting applications to only static or slowly varying strain or temperature environments. To solve this problem, we propose the use of an optical chirp chain probe wave to remove the requirement of frequency sweeping for the Brillouin spectrum, which enables distributed ultrafast strain measurement with a single pump pulse. The optical chirp chain is generated using a frequency-Agile Technique via a fast-frequency-changing microwave, which covers a larger frequency range around the Stokes frequency relative to the pump wave, so that a distributed Brillouin gain spectrum along the fiber is realized. Dynamic strain measurements for periodic mechanical vibration, mechanical shock, and a switch event are demonstrated at sampling rates of 25 kHz, 2.5 MHz and 6.25 MHz, respectively. To the best of our knowledge, this is the first demonstration of distributed Brillouin strain sensing with a wide-dynamic range at a sampling rate of up to the MHz level.
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Wide-range dynamic strain measurements based on K-BOTDA and frequency-Agile Technique
25th International Conference on Optical Fiber Sensors, 2017Co-Authors: Dengwang Zhou, Yongkang Dong, Benzhang Wang, Hongying ZhangAbstract:We propose and demonstrate a novel fast Brillouin optical time-domain analysis system using the coefficient K spectrum which is defined as the ratio of phase-shift and gain of Brillouin amplification, where K features linear response, immune to the variation of pump power and a wide measure range. For a 30ns-square pump pulse, the frequency span of K spectrum can reach up to 200MHz. In dynamic strain experiment, a multi-slope assisted K-BOTDA with the measured strain of 5358.3μe and the vibration frequency of 6.01Hz and 12.05Hz are demonstrated.