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
A new fabricating method is demonstrated to realize two different Bragg gratings in an identical chip using traditional holographic exposure. Polyimide is used to protect one Bragg grating during the first period. The...A new fabricating method is demonstrated to realize two different Bragg gratings in an identical chip using traditional holographic exposure. Polyimide is used to protect one Bragg grating during the first period. The technical process of this method is as simple as that of standard holographic exposure.展开更多
In this paper a Fiber Bragg Grating (FBG) Strain Rosette is designed, developed and tested. Traditional FBGs measure strain in only one direction. However, in-plane strain at a point consists of two normal strains and...In this paper a Fiber Bragg Grating (FBG) Strain Rosette is designed, developed and tested. Traditional FBGs measure strain in only one direction. However, in-plane strain at a point consists of two normal strains and one shear strain. Hence a FBG strain rosette needs to be designed. The sensing principle of FBGs as a strain and temperature sensor and fundamental principles of strain transformation and strain gage rosettes are discussed.FBG strain rosettes are fabricated and embedded in two materials namely, Silicon Gel RTV 146-9 and Glass Fiber Composite Laminates. Experiments were conducted on the FBG strain rosette structures that were embedded in Silicon Gel (RTV 146-9). Initial findings from the experiments as well as preferred embedding material are presented.展开更多
The 3-section SG-DBR tunable laser is fabricate d using an ion implantation quantum-well intermixing process.The over 30nm discontinuous tuning range is achieved with the SMRS greater than 30dB.
We proposed a scheme of fiber Bragg grating （FBG） sensor interrogation system based on all fiber Mach-Zehnder Interferometer （MZI） edge filter and tunable-FBG. The equal power signals from FBG sensor and tunable F...We proposed a scheme of fiber Bragg grating （FBG） sensor interrogation system based on all fiber Mach-Zehnder Interferometer （MZI） edge filter and tunable-FBG. The equal power signals from FBG sensor and tunable FBG are coupled into port 1 and port 2 of MZI respectively. The experimental results show that the interrogation precision of the proposed system is 0.02 nm in a range of I nm. Furthermore, the precision can be improved by adjusting the two interference arms of the filter.展开更多
Measuring amplitude of signal is the usual method in wavelength demodulation of fiber Bragg grating (FBG) sensors recently. This method is easy to be disturbed and has low precision. In this paper, a novel counting wa...Measuring amplitude of signal is the usual method in wavelength demodulation of fiber Bragg grating (FBG) sensors recently. This method is easy to be disturbed and has low precision. In this paper, a novel counting wavelength demodula- tion scheme of FBG sensors using a high birefringent fiber (HBF) loop mirror is reported. This demodulator has simple structure, high precision, cheap price and convenient use. The resolution of the loop mirror device with a HBF of 30 meters long is 0.067 nm. For a center wavelength of FBG of about 1550 nm and a 40 nm shift range of its reflection wavelength, the relative error of measurement is only ± 0.001. This wavelength demodulation device has significance for widespread application of FBG sensors.展开更多
We propose a silica-core dispersion-decreasing Bragg fiber （DDBF） of mode effective area as large as 55 μm^2 for supercontinuum （SO） generation at the pump wavelength of 1060 nm. Using a fast and simple matrix me...We propose a silica-core dispersion-decreasing Bragg fiber （DDBF） of mode effective area as large as 55 μm^2 for supercontinuum （SO） generation at the pump wavelength of 1060 nm. Using a fast and simple matrix method to model propagation in the DDBF,we have presented a general criterion to obtain the shortest length of the DDBF that would result in a broad SO spectrum. The proposed DDBF design should be amenable for reproducible fabrication through the well-developed MCVD fiber manufacturing technology and the concept has potential for realization as a practical device.展开更多
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.
文摘A new fabricating method is demonstrated to realize two different Bragg gratings in an identical chip using traditional holographic exposure. Polyimide is used to protect one Bragg grating during the first period. The technical process of this method is as simple as that of standard holographic exposure.
文摘In this paper a Fiber Bragg Grating (FBG) Strain Rosette is designed, developed and tested. Traditional FBGs measure strain in only one direction. However, in-plane strain at a point consists of two normal strains and one shear strain. Hence a FBG strain rosette needs to be designed. The sensing principle of FBGs as a strain and temperature sensor and fundamental principles of strain transformation and strain gage rosettes are discussed.FBG strain rosettes are fabricated and embedded in two materials namely, Silicon Gel RTV 146-9 and Glass Fiber Composite Laminates. Experiments were conducted on the FBG strain rosette structures that were embedded in Silicon Gel (RTV 146-9). Initial findings from the experiments as well as preferred embedding material are presented.
文摘The 3-section SG-DBR tunable laser is fabricate d using an ion implantation quantum-well intermixing process.The over 30nm discontinuous tuning range is achieved with the SMRS greater than 30dB.
基金This study is supported by National Natural Science Foundation ofChina (No.60507007)National Basic Research Program of China(No. 2003CB314900)Program for New Century ExcellentTalents in University (NCET, Min Zhang 2007).
文摘We proposed a scheme of fiber Bragg grating （FBG） sensor interrogation system based on all fiber Mach-Zehnder Interferometer （MZI） edge filter and tunable-FBG. The equal power signals from FBG sensor and tunable FBG are coupled into port 1 and port 2 of MZI respectively. The experimental results show that the interrogation precision of the proposed system is 0.02 nm in a range of I nm. Furthermore, the precision can be improved by adjusting the two interference arms of the filter.
文摘Measuring amplitude of signal is the usual method in wavelength demodulation of fiber Bragg grating (FBG) sensors recently. This method is easy to be disturbed and has low precision. In this paper, a novel counting wavelength demodula- tion scheme of FBG sensors using a high birefringent fiber (HBF) loop mirror is reported. This demodulator has simple structure, high precision, cheap price and convenient use. The resolution of the loop mirror device with a HBF of 30 meters long is 0.067 nm. For a center wavelength of FBG of about 1550 nm and a 40 nm shift range of its reflection wavelength, the relative error of measurement is only ± 0.001. This wavelength demodulation device has significance for widespread application of FBG sensors.
文摘We propose a silica-core dispersion-decreasing Bragg fiber （DDBF） of mode effective area as large as 55 μm^2 for supercontinuum （SO） generation at the pump wavelength of 1060 nm. Using a fast and simple matrix method to model propagation in the DDBF,we have presented a general criterion to obtain the shortest length of the DDBF that would result in a broad SO spectrum. The proposed DDBF design should be amenable for reproducible fabrication through the well-developed MCVD fiber manufacturing technology and the concept has potential for realization as a practical device.
