【作者】 吴飞；

【导师】 李志全；

【作者基本信息】 燕山大学 ， 测试计量技术及仪器， 2007， 博士

【摘要】 近年来,光纤光栅在光纤传感和光纤通信中的应用研究引起了人们普遍的关注。光纤光栅传感器具有不受电磁干扰、信号带宽大、灵敏度高、易于复用、重量轻、结构紧凑,易于光纤连接,实现波长绝对编码及可以把多个传感器利用各种复用技术连接成传感网络,埋入材料和结构内部或贴装在其表面,实现对其特性的多点监测等优点。这种传感器在大型建筑和油井等特殊场合的安全监测方面具有极为广泛的应用前景。本文主要对光纤光栅在多力参数检测中的反射谱特性进行了理论和实验研究,具体内容包括:介绍了模耦合理论对光纤光栅反射谱模型建立的方法,分析了相关参数对反射谱的影响。从光栅的相位匹配条件出发,对光栅的轴向均匀应变、轴向非均匀应变、温度和应变—温度交叉敏感特性进行了详细的讨论,并建立了相应的数学模型。在研究过程中,对横向均匀负载作用下的光纤光栅反射谱特性进行了详细分析,讨论了其反射谱分裂的原因、两个偏振方向反射谱的受力关系等。同时,应用传输矩阵的方法对光纤光栅横向局部受力特性进行了研究,研究发现当光栅局部受力时,反射谱产生分裂,分裂点波长移动与受力大小成线性周期变化,分裂点的反射率与光栅局部受力位置为双曲正切关系,而且相位也存在一定的关系。在此基础上,对光纤光栅的横向非均匀受力情况进行了研究,分别讨论了线性作用力、正弦型作用力和二次曲线型作用力条件下的光栅反射谱的特性,得到了各种作用力参数与反射谱带宽、对称中心波长等的关系,建立了相应的数学模型。通过对光栅的横向负载特性分析,讨论了其在传感和光纤器件方面的应用前景和重要意义。光纤光栅扭转特性的研究是课题研究的重要部分之一。本文基于高双折射光纤扭转特性和光栅的耦合特性,建立了扭转高双折射光纤光栅的耦合方程,对其反射谱特性与扭转角度的关系进行了研究,并应用传输矩阵的方法进行了验证。研究表明,随着扭转角度的增加,两个偏振方向的光栅反射谱中心波长发生移动且反射率降低,长波长的产生“红移”,短波长的产生“蓝移”,移动的波长量基本相同。同时,在反射谱中产生一个新的谐振峰,其峰值波长为两光栅中心波长之和的1/2,峰值反射率与扭转角度为正切关系。通过对光栅的扭转特性分析,讨论了其在光纤扭曲传感方面的应用价值。针对光纤光栅在不同条件下的反射谱变化特性,提出应用蚁群算法进行光栅反射谱特征分析的构想。通过对蚁群算法模型的建立和程序的设计,分别对光栅轴向受力和横向受力的情况建立了相应的目标函数,并进行了理论仿真实验。实验详细研究了算法各参数对反射谱寻优的影响,并讨论了算法的稳定性、收敛性和准确性。在上述研究的基础上,设计了基于光纤光栅的多力参数测量实验系统,编制了数据采集、处理和谱型分析软件。采用该系统分别对光栅受轴向应变、横向应变和扭转作用进行了实验,获取了相应的实验数据和光谱,并将实验数据与理论分析进行了对比,验证了理论的正确性。同时,应用蚁群算法对光栅横向载荷时的实验结果进行了寻优,得到了更加精确的结果,说明了算法的可行性。更多还原

【Abstract】 In recent years, the applications of fiber Bragg grating (FBG) has been attracted great attention in the field of optical sensing and communication. FBG sensor has the advantages of resistance to electromagnetic interference, big signal bandwidth, high sensitivity, easy multiplexing, light weight, compact conformation, easy for fiber connection, realizing wavelength absolute coding, linking many sensors into sensing network using various multiplexing technology, realizing multi-point monitoring to achieve its properties through embedding in the internal structure of materials, or adhibiting on the surface mount, etc. These sensors have extensive prospect in the security monitoring area of the special occasions, such as the large buildings and oil wells. In this paper, theoretical and experimental studies on spectra response of FBG were carried on in the sensing of the multi-mechanics parameters, which specifically includes:The establishment of FBG’s reflected spectrum model was introduced based on coupled mold theory. The effect of correlation parameter on the reflected spectrum was analyzed. Embark on the phase matching condition of FBG, the detailed discussion was carried on based on axial homogenous strain, axial inhomogeneous strain, cross-sensitivity characteristic of temperature and strain. And the corresponding mathematical model was established.During the research process, the paper analyzes the spectra response of FBG under transverse force in detail. The reason that the reflected spectra of FBG split under transverse force, the stress relation of reflected spectra on the two polarization directions were discussed. At the same time, the characteristic of FBG under local transverse force were studied based on transfer matrix method. The spectrum split with the increase of local transverse force and the split point shift linearly and periodically. The relationship between the reflectivity and the position of stress is hyperbolic tangent. Moreover, the phase had certain relations. Based on this, the characteristic of FBG under inhomogeneous transverse force were studied. The characteristic of FBG under linear force, sinusoidal force and conic force were discussed, respectively. The relation between parameters of transverse force and bandwidth, symmetrical wavelength of spectra were deduced, and the corresponding mathematical model was established. The application prospect and the vital significance were discussed in the field of optical sensing and fiber component, through analysis on the characteristic of FBG under transverse load.Study on the characteristic of twisted HiBi fiber grating is one of the most important parts of the subject study. The paper analyzes the spectra response of twisted HiBi fiber grating. Based on the characteristic of twisted HiBi fiber and coupled mold theory of FBG, the coupled equation of twisted HiBi fiber grating is proposed and proved by transfer matrix method. The study indicates that the center wavelength of FBG’s reflected spectrum on the two polarization directions shift, and the reflectivity decreased with the increase of the twist angle. The longer wavelength produces“red shift”. The shorter wavelength produces“blue shift”. And the wavelength shift is basically same. At the same time, a new resonance peak is produced in the reflected spectrum. Its peak wavelength is 1/2 of the sum of two FBG’s center wavelengths. The relation between peak reflectivity and twist angle is tangent. Through characteristic analysis on the twisted fiber grating, the application value is discussed in the field of fiber-optic torsion sensing.Considering the characteristics of FBG’s reflected spectrum under the different condition, the conception of analysis on characteristic of FBG’s reflected spectrum using the ant colony algorithm is proposed. Through establishment of the ant colony algorithm model and design of the programs, the corresponding objective functions were established respectively to the response of FBG under axial strain and the transverse force, and the theoretical simulation experiment had been carried on. The effects on optimizing of the reflected spectrum were studied in detail based on various parameters of algorithm. And stability, astringency and accuracy of the algorithm were discussed.Based on the above research, the multi-mechanics parameters sensing experiment system of FBG has been designed, and the software of the data acquisition, processing and the simple spectrum analysis has been established. Using this system the experiments were carried on respectively to FBG under the axial strain, the transverse strain and the twisted action. The corresponding experimental data and the spectrum were gained. The comparison between the experimental data and theoretical analysis was given. And the theory had been confirmed accuracy. At the same time, we carried on the optimization to experimental result of FBG under transverse load using ant colony algorithm, obtained a more precise result, and proved the feasibility of the algorithm.更多还原