【作者】 张锦龙；

【导师】 余重秀； 王葵如；

【作者基本信息】 北京邮电大学 ， 电磁场与微波技术， 2009， 博士

【摘要】 光纤传感器技术是通过传感器从自然信源获取信息,并对信息进行处理和识别的一门多学科交叉的现代科学,它与通信技术、计算机技术构成信息产业的三大支柱。该技术涉及到激光技术、纤维光学、非线性光学、电子技术、计算机技术、通信技术、信号处理技术等多个学科和领域。随着传感技术的深入研究与应用,光纤光栅传感技术正要向着网络化、智能化和实用化方向发展,传感解调技术也将向着高速度、高精度和分布式测量等方向发展。本文在调研光纤传感的特点和其在军事、民用领域的应用以及国内外研究进展的基础上,研究了光纤光栅传感技术：分析了光纤光栅传感解调技术的优、劣势,以及今后研究的方向与待解决的技术难点；依据耦合模理论分析方法研究了光纤光栅的光学特性和传感机理；总结了光纤光栅的分类及各类型光纤光栅的制作方法；对多种光纤光栅传感器和解调方案进行了系统的理论和实验研究,设计了四种传感器和三种解调结构,并成功构建了光纤光栅无线传感网络。其主要研究工作和创新成果(黑体部分)如下：针对光纤光栅传感技术实用化中的交叉敏感问题,设计了渐变型等强度悬臂梁结构,研究其对光纤光栅调谐的温度补偿机理,实验验证了该悬臂梁对光纤光栅线性、无啁啾的调谐和温度补偿。采用渐变型悬臂梁调谐光纤布拉格光栅(FBG),通过测定光栅反射谱双峰的位置,使用一根光栅实现了应力和温度双参量同时传感测量。应力和温度传感的灵敏度分别为KF=0.125nm/N和KT=0.0124nm/℃。设计并实现了基于带宽检测的啁啾光纤光栅位移传感器,通过测定啁啾光栅反射谱带宽实现位移的测定,位移传感的灵敏度为K=0.05nm/mm。设计并实现了基于光强检测的啁啾光纤光栅位移传感器。该系统利用电路方法测定光强,提高了测量精度并降低了成本。位移传感的灵敏度为K=0.58pm/mm。研究FBG化学浓度传感器,对丙二醇溶液浓度的测量进行了实验研究,分析了温度敏感对化学浓度的影响及其去敏方法。通过测定溶液折射率的变化实现其对浓度的检测。设计并实现了基于交叉相位调制(XPM)技术的锁相光纤光栅传感器解调系统。采用XPM技术避免了压电陶瓷(PZT)等机械结构的使用,大大提高了系统速度和可重复性,对温度的测量精度可达0.1℃。分析了外界环境对M-Z结构的影响,并提出以LiNbO3波导器件克服环境对干涉器件影响的改进方案。设计了基于保偏型光纤环镜的波长解调系统,分析了其输入光波长和输出光功率分配特性,进行数值仿真并搭建了解调系统。通过调节保偏光纤长度、耦合器耦合系数、保偏光纤主轴角度,实现对测量范围和系统分辨率的调控,并能通过软件自动测定其结构参数。系统在解调范围大于1 nm时,分辨率小于1pm,测量精度小于±1pm。设计了采用保偏光纤和偏振分束器构建干涉仪的传感解调方案,仿真分析了系统结构参数对输出光强与波长对应关系的影响,并搭建实验系统。系统通过调节保偏光纤长度、保偏光纤主轴角度,实现对测量范围和系统分辨率的调控,在解调范围大于1nm时,分辨率小于1pm,测量精度小于±1pm。基于LabVIEW软件平台开发了针对不同传感解调方案的光纤光栅传感解调控制软件,成功地应用于不同机理、不同结构FBG传感器的结构参数测定、数据处理和实时二维图像显示。该软件是传感系统能够脱离实验室,进入应用领域的关键,具有通用性。论文最后对研究工作进行了总结,给出了进一步研究的方向。更多还原

【Abstract】 The technology of fiber sense is an intersectant science of multiply subjects which obtains information from nature, processes and recognizes it using a sensor, and it constitutes there backbones associated with the communication and computer technology. This technology mainly refers to fiber optics, nonlinear optics, and corresponding technologies of laser, electron, computer, communication, and signal processing, and so on. With further investigation and application of sense technology, the technology of fiber grating sense is developing toward the direction of network, intelligence and practicality. Therefore, the technology of sense and demodulation also will necessarily develop toward the direction of measuring at high speed, high precision and distribution.This paper probes into the characteristics of fiber sense and its applications in the field of military affairs and civilization applications as well as research progress at home and abroad, and the investigation on Fiber Bragg Grating Sensor is carried out: analyzing the technology advantage and disadvantage of sense and demodulation of fiber grating, the further direction of investigation and technology difficulties unsolved; investigating the optical characteristics and sense mechanism of fiber grating based on coupling-mode theory; summarizing the classification and fabrication techniques of fiber grating; studying a number of schemes of sense and demodulation of fiber grating theoretically and experimentally; designing some structures of sense and demodulation and constructing network of wireless sense based on fiber grating successfully. The innovative works are primarily as follows:A kind of structure with gradient strength and double-triangle cantilever for investigating the compensation mechanism of temperature on tuning of fiber grating is designed aiming at cross-sensitive issues in actual use of sense technology of fiber grating. The linear and chirp-free tuning and temperature compensation of this structure on fiber grating are verified experimentally. The stress and temperature sensing parameters are measured in one grating at the same time using Fiber Bragg Grating with gradient strength, double-triangle cantilever structure through measuring the two peak locations of reflection spectrum of grating. The sensitivities of stress and temperature sense are KF=0.125nm/N and KT=0.0124nm/℃,respectively.Having designed and achieved the shift-sensor based on chirp fiber grating of bandwidth detection, the measurement of shift is implemented through determining the reflection spectrum of chirp grating, and the sensitivity of shift sensing can achieve up to K=0.05 nm/mm.Having designed and achieved the shift-sensor based on chirp fiber grating of light intensity detection, this system enhances precision of measurement and reduces cost through utilizing circuit method to determine light intensity, and the sensitivity of shift sensing can achieve up to K=0.58pm/mm.Having developed the FBG sensor of chemical concentration, the concentration of propylene glycol solution is measured experimentally, and the influence of temperature-sensitivity on chemical concentration and the method of eliminating sensitivity are analyzed. The detection of concentration is achieved by measuring changes in the refractive index of solution.Having designed and achieved the demodulation system of the phase-locked fiber grating sensor based on cross-phase modulation (XPM) technology, the uses of mechanical structures such as PZT, and so on are avoided because of XPM technology, the speed and repeat of system are greatly enhanced, and the precision of measurement on temperature can achieve up to 0.1℃.Furthermore, the influence of surrounding environment on the structure of M-Z is analyzed, and the improved scheme for overcoming the influence of temperature on parts of an apparatus of interference based on LiNbO3 waveguide devices is put forward.Having designed the system of wavelength-demodulation based on the loop mirror with polarization-keeping fiber, the distribution characteristics between the input wavelengths and output powers is analyzed with the numerical simulation being carried out, and the demodulation is established. Moreover, the scope of measurement and resolution of system are controlled through adjusting the length of polarization-keeping fiber, the coupling coefficient of coupling devices, and the main-axis angles of polarization-keeping fiber with the structure parameters being determined by software. The resolution and precision of demodulation system are less than 1pm and±1pm in a much wider scope of above 1nm, respectively.Having designed the schemes of sense and demodulation of establishing interferometer based on polarization-keeping fiber and polarization beam-splitter, the influences of structure parameters of system on the corresponding relationship of output light intensities and wavelengths are simulated numerically, and the experimental system is established. The scope of measurement and resolution of system are controlled through adjusting the length of polarization-keeping fiber, and the main-axis angles of polarization-keeping fiber. The resolution and precision of demodulation system are less than lpm and±1pm within 1nm, respectively.Having developed controllable software for sense and demodulation of fiber grating aiming at different schemes of sense and demodulation based on Lab VIEW platform, and apply successfully it to the determination of structure parameters, data processing and display of two dimension image of FBG sensor with different principles and structures. This software is crucial for sense system to depart from lab and enter into the field of application.Finally, all works investigated are summarized, and the further direction of study is indicated.更多还原