Sampled fiber grating is a special superstructure fiber Bragg grating with a wide range of applications in many fields.In this work,based on drawing tower in-line fabrication system,a new preparation method of the sam...Sampled fiber grating is a special superstructure fiber Bragg grating with a wide range of applications in many fields.In this work,based on drawing tower in-line fabrication system,a new preparation method of the sampled fiber grating is proposed and experimentally demonstrated.Experimental result shows that the obtained sampled fiber gratings possess dense reflection spectra,with a minimum reflection peak interval of only 0.09 nm.This method exhibits promising application prospect in the fabrication of the high-quality sampled fiber grating.On the other hand,the spectral characteristics of the sampled fiber grating are analyzed when the sub-grating is affected by the external physical quantities such as,in this paper,strain.Wavelength shift and intensity change in the reflection peak of the spectra indicate that the grating is affected differently by micro strains,due to the different spatial positions along the axis of the sampled fiber grating.This work is aimed at exploring the potential applications of the sampled fiber grating in quasi-distributed micro-area sensing with the millimeter level.展开更多
A distributed fiber optic interferometric geophone array based on draw tower grating （DTG） array is proposed. The DTG geophone array is made by the DTG array fabricated based on a near-contact exposure through a pha...A distributed fiber optic interferometric geophone array based on draw tower grating （DTG） array is proposed. The DTG geophone array is made by the DTG array fabricated based on a near-contact exposure through a phase mask during the fiber drawing process. A distributed sensing system with 96 identical DTGs in an equal separation of 20 m and an unbalanced Michelson interferometer for vibration measurement has been experimentally validated compared with a moving-coil geophone. The experimental results indicate that the sensing system can linearly demodulate the phase shift. Compared with the moving coil geophone, the fiber optic sensing system based on DTG has higher signal-to-noise ratio at low frequency.展开更多
Marine monitoring faces significant challenges due to the vast spatial scale and subtle variations in environmental parameters,necessitating distributed sensor systems with exceptional sensitivity and multiplexing cap...Marine monitoring faces significant challenges due to the vast spatial scale and subtle variations in environmental parameters,necessitating distributed sensor systems with exceptional sensitivity and multiplexing capabilities.While existing high-sensitivity fiber optic sensors lack sufficient multiplexing capacity for large-scale deployment,we present a novel distributed sensing scheme integrating Fabry-Perot interferometers(FPIs)with draw-tower gratings(DTGs).Each FPI is constructed through two adjacent DTGs interconnected via functionalized sensing fibers with distinct coating materials to decouple the mutual cross-sensitivity between temperature and pressure.Through mechanical capsulation with a pressure-sensitive copper tube,hydrostatic pressure-induced deformation creates measurable axial strain gradients in the optical fiber,achieving enhanced depth sensitivity.The experimental results show that the sensor exhibits good linear responses(R^(2)>0.99)across tested parameter ranges,with measured temperature and depth sensitivities of12,784 rad/℃and 801 rad/m,respectively,consistent with theoretical models.The system achieves remarkable resolution of 1.56×10^(-5)℃(temperature)and 2.50×10^(-4)m(depth)through phase-sensitive detection.Leveraging the ultra-weak reflectivity of DTGs and the compatibility of the sensing array with the Michelson interferometer(MI),the sensing structure exhibits excellent multiplexing capability.With advantages of high sensitivity,unprecedented resolution,and ease of multiplexing,the structure possesses significant potential as an efficient solution for distributed measurements in marine engineering.展开更多
This paper reports on an experimental program of work which investigates the reliability, durability, and packaging of fiber Bragg gratings （FBGs） for application as distributed strain sensors during structural fati...This paper reports on an experimental program of work which investigates the reliability, durability, and packaging of fiber Bragg gratings （FBGs） for application as distributed strain sensors during structural fatigue testing of military platforms. The influence of the FBG fabrication process on sensor reliability is investigated. In addition, methodologies for broad-area packaging and surface-mounting of FBG sensing arrays to defense platforms are developed and tested.展开更多
基金This work was supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.61290311 and 61735013)the Major Scientific and Technological Innovation Project in Hubei Province(Grant No.2015AAA001).
文摘Sampled fiber grating is a special superstructure fiber Bragg grating with a wide range of applications in many fields.In this work,based on drawing tower in-line fabrication system,a new preparation method of the sampled fiber grating is proposed and experimentally demonstrated.Experimental result shows that the obtained sampled fiber gratings possess dense reflection spectra,with a minimum reflection peak interval of only 0.09 nm.This method exhibits promising application prospect in the fabrication of the high-quality sampled fiber grating.On the other hand,the spectral characteristics of the sampled fiber grating are analyzed when the sub-grating is affected by the external physical quantities such as,in this paper,strain.Wavelength shift and intensity change in the reflection peak of the spectra indicate that the grating is affected differently by micro strains,due to the different spatial positions along the axis of the sampled fiber grating.This work is aimed at exploring the potential applications of the sampled fiber grating in quasi-distributed micro-area sensing with the millimeter level.
基金Acknowledgment This work was partly supported by the Major Program of the National Natural Science Foundation of China （Grant No. 61290311）, the Fundamental Research Funds for the Central Universities （Grant No. 2015Ⅲ056）, and Key Consulting Project of Chinese Academy of Engineering （Grant No. 2016-XZ-13）.
文摘A distributed fiber optic interferometric geophone array based on draw tower grating （DTG） array is proposed. The DTG geophone array is made by the DTG array fabricated based on a near-contact exposure through a phase mask during the fiber drawing process. A distributed sensing system with 96 identical DTGs in an equal separation of 20 m and an unbalanced Michelson interferometer for vibration measurement has been experimentally validated compared with a moving-coil geophone. The experimental results indicate that the sensing system can linearly demodulate the phase shift. Compared with the moving coil geophone, the fiber optic sensing system based on DTG has higher signal-to-noise ratio at low frequency.
基金supported by the National Natural Science Foundation of China(Nos.62275204 and 52071245)the Key Research and Development Program of Hubei Province(No.2023DJC170)。
文摘Marine monitoring faces significant challenges due to the vast spatial scale and subtle variations in environmental parameters,necessitating distributed sensor systems with exceptional sensitivity and multiplexing capabilities.While existing high-sensitivity fiber optic sensors lack sufficient multiplexing capacity for large-scale deployment,we present a novel distributed sensing scheme integrating Fabry-Perot interferometers(FPIs)with draw-tower gratings(DTGs).Each FPI is constructed through two adjacent DTGs interconnected via functionalized sensing fibers with distinct coating materials to decouple the mutual cross-sensitivity between temperature and pressure.Through mechanical capsulation with a pressure-sensitive copper tube,hydrostatic pressure-induced deformation creates measurable axial strain gradients in the optical fiber,achieving enhanced depth sensitivity.The experimental results show that the sensor exhibits good linear responses(R^(2)>0.99)across tested parameter ranges,with measured temperature and depth sensitivities of12,784 rad/℃and 801 rad/m,respectively,consistent with theoretical models.The system achieves remarkable resolution of 1.56×10^(-5)℃(temperature)and 2.50×10^(-4)m(depth)through phase-sensitive detection.Leveraging the ultra-weak reflectivity of DTGs and the compatibility of the sensing array with the Michelson interferometer(MI),the sensing structure exhibits excellent multiplexing capability.With advantages of high sensitivity,unprecedented resolution,and ease of multiplexing,the structure possesses significant potential as an efficient solution for distributed measurements in marine engineering.
文摘This paper reports on an experimental program of work which investigates the reliability, durability, and packaging of fiber Bragg gratings （FBGs） for application as distributed strain sensors during structural fatigue testing of military platforms. The influence of the FBG fabrication process on sensor reliability is investigated. In addition, methodologies for broad-area packaging and surface-mounting of FBG sensing arrays to defense platforms are developed and tested.
