A simple and inexpensive sensing structure,single mode fiber(SMF)alignment fusion to 62.5μm stepped index-multimode fiber(SI-MMF),combined with Brillouin optical time domain reflectometry(BOTDR)system,is used as a di...A simple and inexpensive sensing structure,single mode fiber(SMF)alignment fusion to 62.5μm stepped index-multimode fiber(SI-MMF),combined with Brillouin optical time domain reflectometry(BOTDR)system,is used as a distributed sensor in the field of structural safety and health monitoring(SSHM)of large infrastructures in terms of its prominent bending resistance.The bend loss principle and influencing factors of the fiber are analyzed,and the bending resistances of different fibers are discussed on the basis of theoretical and experimental comparisons.The bend-tolerant capacity and temperature sensing characteristics of the 5 km sensing structure are measured by using the self-developed frequency-shifted local heterodyne BOTDR system.The results show that the proposed sensing structure has excellent bend-tolerant capacity with a minimum bend radius and temperature measurement error of 1.25 mm and 0.69℃,respectively,which indicates that the proposed sensing structure has huge potential in the field of SSHM of large infrastructures.展开更多
Distributed optical fiber sensor based on Brillouin scat- tering was fn＇st proposed by Farahi et al in 1989[1], and has attracted intense interest due to the potential applica- tion in monitoring large civil structur...Distributed optical fiber sensor based on Brillouin scat- tering was fn＇st proposed by Farahi et al in 1989[1], and has attracted intense interest due to the potential applica- tion in monitoring large civil structures, power cables, oil and gas pipelines and geological disaster[2＇3]. One of the subjects mainly investigated is Brillouin optical time domain reflectometer （BOTDR） for single-fiber-ended measurement only and simple implementation. The backscattered spontaneous light is used to measure the round-trip time of optical pulses entering into the sens- ing fiber and the optical intensity at each sampling point. By analyzing the measured round-trip time and the spon- taneous Brillouin intensity, the distributed physical quantities, such as temperature and strain, can be ob- tained [4,5].展开更多
基金supported by the National Natural Science Foundation of China(Nos.61775057 and 51607066)the Natural Science Foundation of Hebei Province of China(Nos.F2019502112 and E2019502177)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.2019MS086 and 2021MS071)the S&T Program of Hebei(No.SZX2020034)。
文摘A simple and inexpensive sensing structure,single mode fiber(SMF)alignment fusion to 62.5μm stepped index-multimode fiber(SI-MMF),combined with Brillouin optical time domain reflectometry(BOTDR)system,is used as a distributed sensor in the field of structural safety and health monitoring(SSHM)of large infrastructures in terms of its prominent bending resistance.The bend loss principle and influencing factors of the fiber are analyzed,and the bending resistances of different fibers are discussed on the basis of theoretical and experimental comparisons.The bend-tolerant capacity and temperature sensing characteristics of the 5 km sensing structure are measured by using the self-developed frequency-shifted local heterodyne BOTDR system.The results show that the proposed sensing structure has excellent bend-tolerant capacity with a minimum bend radius and temperature measurement error of 1.25 mm and 0.69℃,respectively,which indicates that the proposed sensing structure has huge potential in the field of SSHM of large infrastructures.
基金supported by the National Natural Science Foundation of China(No.61775057)the Natural Science Foundation of Hebei Province of China(Nos.E2015502053 and F2015502059)
文摘Distributed optical fiber sensor based on Brillouin scat- tering was fn＇st proposed by Farahi et al in 1989[1], and has attracted intense interest due to the potential applica- tion in monitoring large civil structures, power cables, oil and gas pipelines and geological disaster[2＇3]. One of the subjects mainly investigated is Brillouin optical time domain reflectometer （BOTDR） for single-fiber-ended measurement only and simple implementation. The backscattered spontaneous light is used to measure the round-trip time of optical pulses entering into the sens- ing fiber and the optical intensity at each sampling point. By analyzing the measured round-trip time and the spon- taneous Brillouin intensity, the distributed physical quantities, such as temperature and strain, can be ob- tained [4,5].
