基于偏振模耦合的分布式应力传感研究

发布时间：2018-10-20 13:41

【摘要】：分布式光纤传感是一种以光纤为传感介质并获取随时间与空间分布信息的技术,其中基于光频域反射(OFDR)并结合偏振模耦合的分布式应力传感系统具有较高的空间分辨率。本论文首先对保偏光纤耦合强度与应力之间的关系进行了深入的研究;然后根据OFDR系统结构,分析了系统性能参数与相位噪声模型,并对系统中可调谐光源非线性效应的影响进行了研究;最后搭建了基于OFDR与偏振模耦合相结合的分布式应力传感系统实验平台,并进行了相关的实验研究。主要内容如下:1.根据弹光效应与偏振模耦合理论对保偏光纤耦合强度随应力大小和角度的变化关系进行了理论推导,得到了偏振耦合强度与应力之间的解析式,并进行了相应的仿真分析和实验验证,结果表明:当应力大小F一定时,保偏光纤耦合强度h随应力作用角度θ的变化呈现出以π/2为周期的正弦变化关系;当应力作用角度?一定,且应力大小F较小时,保偏光纤耦合强度h随应力大小F呈近似线性变化。2.设计了基于M-Z干涉仪结构的OFDR光路系统,并研究了系统相位噪声模型与可调谐光源非线性效应的影响。深入分析了非均匀傅里叶变换、去斜滤波器、三次样条插值等三种对光源非线性效应进行补偿的算法,并采用Labview软件分别对三种补偿算法进行了模拟仿真,结果表明:三种补偿方法均可实现对光源非线性效应的补偿。其中,三次样条插值算法具有原理简单,运算精度更高等优点,更适合于OFDR系统可调谐光源非线性效应的补偿。3.完成了基于OFDR的分布式应力传感实验系统的搭建与测试。实验中通过对测试数据的非线性补偿,实现了最高空间分辨率为4 cm;在此基础上,对光纤在单点与多点施加应力的情况下分别进行了测试,结果表明该系统能够检测出应力的位置信息和应力大小的变化。该系统定位测量误差为?0.6 m,应力大小测量误差为?9.7%。通过以上几方面的研究,最终实现了基于OFDR并结合保偏光纤偏振模耦合的分布式应力传感系统,并且能够有效地进行高空间分辨率的分布式应力测试,在分布式光纤传感技术的研究与发展中具有重要意义。
[Abstract]:Distributed optical fiber sensing is a kind of technology which takes optical fiber as the sensor medium and acquires information with time and space. The distributed stress sensing system based on optical frequency domain reflection (OFDR) and polarization mode coupling has high spatial resolution. In this paper, the relationship between coupling strength and stress of polarization-maintaining fiber is studied, and then the performance parameters and phase noise model are analyzed according to the structure of OFDR system. Finally, the experimental platform of distributed stress sensing system based on OFDR and polarization mode coupling is built, and the related experimental research is carried out. The main contents are as follows: 1. Based on the elastic-optical effect and polarization mode coupling theory, the relationship between the coupling strength of polarization maintaining fiber with stress and angle is derived theoretically, and the analytical formula between polarization coupling strength and stress is obtained. The corresponding simulation analysis and experimental results show that when the stress F is constant, the coupling strength h of the polarization-maintaining fiber changes with the stress angle 胃, and takes 蟺 / 2 as the period of sinusoidal change, and when the stress action angle is constant, the variation of the coupling strength of the polarization maintaining fiber shows a sine relation with the stress action angle 胃. The coupling strength h of the polarization-maintaining fiber changes linearly with the stress magnitude F when the stress F is small. 2. The OFDR optical circuit system based on M-Z interferometer structure is designed and the influence of the system phase noise model and the nonlinear effect of tunable light source is studied. The nonuniform Fourier transform, de-skew filter and cubic spline interpolation are analyzed to compensate the nonlinear effect of the light source. The simulation of the three compensation algorithms is carried out by using Labview software. The results show that all three methods can compensate the nonlinear effect of light source. Among them, the cubic spline interpolation algorithm has the advantages of simple principle and high precision, and is more suitable for compensating the nonlinear effect of tunable light source in OFDR system. The distributed stress sensing experiment system based on OFDR is built and tested. In the experiment, the maximum spatial resolution of 4 cm; is realized by nonlinear compensation of the test data. On the basis of this, the fiber is tested under the condition of single point and multi-point stress. The results show that the system can detect the position information of stress and the change of stress. The error of position measurement is 0.6 m, and the error of stress measurement is? 9.7 m. Finally, the distributed stress sensing system based on OFDR and polarization mode coupling of polarization maintaining fiber is realized, and the distributed stress measurement with high spatial resolution can be carried out effectively. It is of great significance in the research and development of distributed optical fiber sensing technology.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN253

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