针对峰值检测法的不足,提出了频谱相关技术和数字滤波技术,以提高光纤Bragg光栅(FBG)传感系统波长偏移检测精度。分别对峰值检测(CPD)法、数字滤波(CHEBY and IDEAL)法和频谱相关(SC)法检测波长偏移进行了数值模拟,并且搭建了实验系统,...针对峰值检测法的不足,提出了频谱相关技术和数字滤波技术,以提高光纤Bragg光栅(FBG)传感系统波长偏移检测精度。分别对峰值检测(CPD)法、数字滤波(CHEBY and IDEAL)法和频谱相关(SC)法检测波长偏移进行了数值模拟,并且搭建了实验系统,对实验数据进行具体分析计算,证实了理论分析的正确性。理论和实验证明,SC法可提高解调检测的精确度,达到理想低通滤波(IDEAL)法的效果。展开更多
In this weigh-in-motion(WIM)research,a novel fiber Bragg grating(FBG)-based weigh-in-motion(WIM)system was introduced.The design derived from the idea using in-service bridge abutments as the weigh scale.The bridge be...In this weigh-in-motion(WIM)research,a novel fiber Bragg grating(FBG)-based weigh-in-motion(WIM)system was introduced.The design derived from the idea using in-service bridge abutments as the weigh scale.The bridge beam was replaced by a piece of steel plate which supports the weight of the traveling vehicle.All weights would be finally transferred into the tubes where four FBGs were attached and could record the weight-induced strains by shifting their Bragg wavelengths.The system identification algorithm based on parameters estimation was initiated.Over 40-ton load had been applied on the system and the experimental results showed a good repeatability and linearity.The system resolution had been achieved as low as 10 kg.Compared with other designs of fiber-optic WIM systems,this design is easy and reliable.展开更多
The optical wavelet filter is designed. It can filter and choose frequency swiftly. It can realize demodulation of distributed fiber Bragg grating（FBG） measurement system. Its scanning resolution and scanning period...The optical wavelet filter is designed. It can filter and choose frequency swiftly. It can realize demodulation of distributed fiber Bragg grating（FBG） measurement system. Its scanning resolution and scanning period depend on wavelet function. Wavelet function is controlled by computer. Compared to conventional scan filter, optical wavelet filtering has some advantages such as simple structure, high scan frequency, high resolution and good linearity. At last, the error of optical wavelet filter scanning procedure is analyzed. Scanning step length refers to the shifting of optical wavelet window＇s central frequency. It affects system precision directly. If scanning step length is different, the measured signal is different. The methods of reducing step length guarantee scanning periodic time are presented.展开更多
Several high-performance and tunable erbium-doped fiber lasers are reviewed. They are constructed by using fiber Bragg gratings (FBGs) or short-wavelength-pass filters (SWPFs) as wavelength tunable components inside t...Several high-performance and tunable erbium-doped fiber lasers are reviewed. They are constructed by using fiber Bragg gratings (FBGs) or short-wavelength-pass filters (SWPFs) as wavelength tunable components inside the laser cavity. Broadband wavelength tuning range including C- and/or S-band was achieved, and tunable laser output with high slope efficiency, high side-mode suppression ratio was obtained. These fiber lasers can find vast applications in lightwave transmission, optical test instrument, fiber-optic gyros, spectroscopy, material processing, biophotonic imaging, and fiber sensor technologies.展开更多
文摘针对峰值检测法的不足,提出了频谱相关技术和数字滤波技术,以提高光纤Bragg光栅(FBG)传感系统波长偏移检测精度。分别对峰值检测(CPD)法、数字滤波(CHEBY and IDEAL)法和频谱相关(SC)法检测波长偏移进行了数值模拟,并且搭建了实验系统,对实验数据进行具体分析计算,证实了理论分析的正确性。理论和实验证明,SC法可提高解调检测的精确度,达到理想低通滤波(IDEAL)法的效果。
文摘In this weigh-in-motion(WIM)research,a novel fiber Bragg grating(FBG)-based weigh-in-motion(WIM)system was introduced.The design derived from the idea using in-service bridge abutments as the weigh scale.The bridge beam was replaced by a piece of steel plate which supports the weight of the traveling vehicle.All weights would be finally transferred into the tubes where four FBGs were attached and could record the weight-induced strains by shifting their Bragg wavelengths.The system identification algorithm based on parameters estimation was initiated.Over 40-ton load had been applied on the system and the experimental results showed a good repeatability and linearity.The system resolution had been achieved as low as 10 kg.Compared with other designs of fiber-optic WIM systems,this design is easy and reliable.
基金This project is supported by National Natural Science Foundation of China(No.60377002).
文摘The optical wavelet filter is designed. It can filter and choose frequency swiftly. It can realize demodulation of distributed fiber Bragg grating（FBG） measurement system. Its scanning resolution and scanning period depend on wavelet function. Wavelet function is controlled by computer. Compared to conventional scan filter, optical wavelet filtering has some advantages such as simple structure, high scan frequency, high resolution and good linearity. At last, the error of optical wavelet filter scanning procedure is analyzed. Scanning step length refers to the shifting of optical wavelet window＇s central frequency. It affects system precision directly. If scanning step length is different, the measured signal is different. The methods of reducing step length guarantee scanning periodic time are presented.
文摘Several high-performance and tunable erbium-doped fiber lasers are reviewed. They are constructed by using fiber Bragg gratings (FBGs) or short-wavelength-pass filters (SWPFs) as wavelength tunable components inside the laser cavity. Broadband wavelength tuning range including C- and/or S-band was achieved, and tunable laser output with high slope efficiency, high side-mode suppression ratio was obtained. These fiber lasers can find vast applications in lightwave transmission, optical test instrument, fiber-optic gyros, spectroscopy, material processing, biophotonic imaging, and fiber sensor technologies.
