【作者】 张治国；

【导师】 叶培大；

【作者基本信息】 北京邮电大学 ， 电磁场与微波技术， 2007， 博士

【摘要】 光纤传感是以光波为载体，光纤为煤质，感知和传输外界被测信号的新型传感技术。光纤传感技术因具有灵敏度高、体小质轻、外形改变灵活、抗电磁干扰、抗腐蚀性强等特点，自出现之日其就广泛应用于社会的多个领域。近年来新型微结构光纤的出现在促进光通信技术发展的同时，其传感特性也显现出诱人的应用前景。对微结构光纤传感特性的深入研究将会极大提升光纤传感技术并推动其应用领域的拓展。随着光纤传感技术应用市场的不断扩展，对高精度、低成本、商用化光纤光栅传感及解调系统的研究同样具有重要意义。本论文主要是微结构光纤气液体传感及光纤光栅传感解调系统等方面的理论和实验工作。研究内容主要分两方面：一方面，通过数值仿真的方法，分析微结构光纤的结构和传输参数对其气液体传感特性的影响；另一方面，设计新型光纤光栅传感解调方案，并通过实验的方法，对所提传感解调系统进行性能研究。本论文的主要工作概述如下：第一部分：微结构光纤数值仿真平台的建立及传感特性的仿真分析◇基于对多种用于微结构光纤数值仿真方法的主要特点及适用场合的分析总结，建立了基于全矢量有限元法的微结构光纤数值仿真平台，并根据已发表的实验结果和数值结果，对仿真平台的可靠性和准确性进行了验证。◇建立了分析孔芯光子晶体光纤(PCF)传感特性的数值仿真模型，分析了孔芯PCF的气体及液体传感特性，详细讨论了光纤结构参量及传输光波长对其气液体传感灵敏度的影响；结果表明孔芯PCF孔结构内的电磁场能量分布最高可达总能量的1／2以上，同比是普通光子晶体光纤的四倍。◇建立了分析高折射率芯布拉格(Bragg)光纤传感特性的数值仿真模型，分析了高折射率Bragg光纤的气体传感特性，详细讨论了光纤结构参量对气体传感灵敏度的影响；结果表明高折射率芯Bragg光纤中空气孔中的电磁场能量分布最高可达1／4以上，比普通PCF高出一倍以上。第二部分：新型光纤光栅传感解调系统的实验研究及性能分析◇提出了基于匹配光栅和线型腔拉曼光纤激光器的光纤布拉格光栅(FBG)传感解调系统方案，并进行了实验验证；结果表明该方案具有分布式、高信噪比、高抗干扰性等优点。◇改进了基于线型腔掺铒光纤激光器、环型腔掺铒光纤激光器的FBG传感解调系统，并对此两种系统进行了实验验证：实验结果表明该两种系统具有高信噪比、高抗干扰性、高传感灵敏度等优点。◇提出了基于匹配光纤光栅的FBG传感解调系统方案，并分别利用步进电机和温度调节箱作为调谐装置进行了系统实验验证：实验结果表明该种系统方案具有结构简单、成本低廉，传感灵敏度较高等特点。◇提出了基于马赫-曾德尔干涉仪(MZI)和匹配光纤光栅的FBG传感解调系统方案，并进行了实验验证，实验结果表明，此方案具有结构新颖、传感灵敏度高，全光结构等优点。更多还原

【Abstract】 Fiber-optic sensor, a novel sensor technology that provides measuring and monitoring solutions for temperature, pressure, strain, displacement, force and load, has attracted a considerable amount of interests in the last decades because of their unprecedented properties, such as self-referencing capability, high signal-to-noise ratio, immunity to electromagnetic interference and anti-cauterization. With the development of the fiber sensor applications, much work on the fiber sensor technology was focused on the research of the sensing properties of microstructured optical fiber (MOF) and the wavelength interrogation systems feature high resolution, low cost, low complexity and high utility.This dissertation mainly focuses on theoretical studies on the sensing properties of MOF and experimental studies on sensing systems of fiber Bragg grating (FBG). The works are made up of two parts, one is the relationships between the gas sensing properties and the fiber parameters of MOF, including the fiber length and the operating wavelength, are numerically investigated through a full-vector finite element method (FEM), another is novel schemes of wavelength interrogation of FBG sensing are proposed and demonstrated. Below are the lists of the research.Gas sensing properties of MOFA full-vector finite element mode solver based on the hybrid edge/nodal element is developed to conduct the numerical simulation of MOF. Perfectly matched layer (PML) boundary conditions are incorporated into the mode solver to evaluate the leakage properties of MOF.The gas sensing properties of index-guided photonic crystal fiber (PCF) with air-core are investigated via full-vector FEM. The fraction of the total power located in the holes (including the air-core), which directly affects the sensing sensitivity, is simulated. The relationship between the gas sensing properties and the fiber parameters, as well as the operating wavelength, is discussed. It is predicted that higher relative sensitivity of more than 50% can be achieved by designing the fiber parameters and the operating wavelength properly.The gas sensing properties of high-index-core Bragg fiber are investigated via full-vector FEM. The fraction of the total power located in the holes is simulated. The relationship between the gas sensing properties and the fiber parameters, as well as the operating wavelength, is discussed. It is predicted that the gas sensing sensitivity of the fiber increases with the fiber’s radius and refractive index decrease, but increases with the wavelength increase.Wavelength interrogation schemes of FBGA scheme of long-distance FBG sensor system based on linear-cavity fiber Raman laser is firstly proposed and demonstrated. Two schemes of FBG wavelength demodulation based on tunable Er-doped fiber ring laser and linear-cavity Er-doped fiber laser are improved, respectively. In measured experiment, results show that the schemes based on fiber laser feature high Signal-to-Noise ratio (SNR), high sensitivity, and anti-jamming.Two schemes of FBG interrogation system based on matching-FBG are proposed and demonstrated, in which step motor and temperature control equipment are used to adjust the matching-FBG, respectively. In measured experiments, results show that the schemes based on matching-FBG feature low cost, small size, low complexity and high utility.A scheme of FBG sensor interrogation system based on all fiber Mach-Zehnder interferometer (MZI) edge filter and tunable-FBG is firstly proposed and demonstrated. The sensing signal produced by FBG sensor can be interrogated by differing two pairs of power transformed from the wavelengths of FBG sensor and tunable-FBG. In measured experiments, the results show that the precision of the proposed system is 0.02nm in a range of 1nm. Furthermore, the precision can be improved by adjusting the two interference arms of the filter.更多还原