基于多模光纤光斑检测的模式分析和光谱分析研究

发布时间：2018-04-19 16:52

本文选题：光纤传感 + 光斑检测　；参考：《北京交通大学》2017年硕士论文

【摘要】：随着数字信号处理技术的发展和成像技术的日益普及,基于光纤光斑检测的各项技术的复杂程度和成本大幅降低,促进了光纤光斑检测在传感以及光谱分析等研究领域的发展。针对目前模式分析领域解析法对波导结构要求严格,而数值分析方法普遍存在着计算精度和计算量之间矛盾的问题,本文提出了基于多模光纤光斑检测技术的波导模式分析方法,并且针对基于光纤光斑检测的光谱分析技术中光纤长度与光谱重建性能之间的矛盾,提出了两种基于改进光纤结构的光谱分析方案。主要的工作内容如下:1、对光斑检测的耦合及多模干涉理论进行了理论分析,并总结归纳了现有的光斑图样处理算法,包括基于光强和基于图像内容的算法。2、针对单模-阶跃多模光纤结构中模式激励情况与光纤轴心偏移程度的关系进行了理论计算,并利用光束传播法获得了多模光纤端面处的光斑图样。将灰度共生矩阵图像处理技术引入光斑图样处理,详细分析了该结构在不同偏心熔接时的端面光斑与图像特征值的关系,得到了激发模式数量和灰度共生矩阵特征值能量、一致性、熵之间的近似线性关系,并在实验环境下进行了验证。之后将此结论应用于分析D型多模光纤的模式激发情况。在常用复杂数值计算方法外,为定性研究光纤内模式激励情况提供了一种新的分析方法。3、对基于多模光纤光斑分析的光谱仪的原理进行了分析,实现了利用光斑检测在噪声环境下重建光源信号的算法,并基于光谱相关宽度实现了光谱分辨率的计算。采用偏芯熔接的单模-阶跃多模光纤结构及单模-D型多模-多模光纤结构取代原有的对芯熔接结构,对该类型光谱仪进行了改进。对改进前后的光谱分析性能进行了比较分析,通过仿真综合比较了光谱重建误差、半波全宽、宽带信号重建三个性能因子,验证了改进后的方案在光谱重建性能上优于原有的结构。
[Abstract]:With the development of digital signal processing technology and the increasing popularity of imaging technology, the complexity and cost of various technologies based on optical fiber spot detection are greatly reduced, which promotes the development of optical fiber spot detection in the field of sensing and spectral analysis.In view of the strict requirement of the waveguide structure for the analytical method in the field of mode analysis at present, the numerical analysis method generally has the problem of the contradiction between the calculation accuracy and the computational complexity.In this paper, a waveguide mode analysis method based on multimode optical spot detection technology is proposed, and the contradiction between optical fiber length and spectral reconstruction performance in spectrum analysis technology based on optical fiber spot detection is discussed.Two spectral analysis schemes based on improved fiber structure are proposed.The main work is as follows: 1. The coupling and multi-mode interference theory of spot detection are analyzed theoretically, and the existing algorithms of spot pattern processing are summarized.Including the algorithm. 2 based on light intensity and image content, the relationship between mode excitation and axis deviation in single-mode step multimode fiber structure is calculated theoretically.The spot pattern at the end face of multimode fiber is obtained by beam propagation method.The gray level co-occurrence matrix image processing technique is introduced to the spot pattern processing, and the relationship between the end spot and the image eigenvalue of the structure under different eccentricity welding conditions is analyzed in detail. The number of excitation modes and the eigenvalue energy of the gray level co-occurrence matrix are obtained.The consistency and the approximate linear relation between entropy are verified in the experimental environment.Then this conclusion is applied to analyze the mode excitation of D-type multimode fiber.In addition to the complex numerical calculation methods, this paper provides a new analytical method for qualitatively studying the internal mode excitation of optical fiber. The principle of the spectrometer based on multimode optical spot analysis is analyzed.The algorithm of reconstruction of light source signal in noisy environment by spot detection is realized, and the spectral resolution is calculated based on spectral correlation width.The single-mode-step multimode fiber structure and single-mode -D type multimode fiber structure are used to replace the original core fusion structure, and the spectrometer is improved.The performance of spectral analysis before and after the improvement is compared and analyzed. The spectral reconstruction error, the full width of half wave and the reconstruction of wideband signal are comprehensively compared by simulation.The improved scheme is superior to the original structure in spectral reconstruction performance.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN253

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