结构调制型超长周期光纤光栅的制作及传感特性研究

发布时间：2018-03-23 12:58

本文选题：结构调制型　切入点：超长周期光纤光栅　出处：《哈尔滨工程大学》2016年博士论文

【摘要】：随着光纤光栅制造业的快速发展,制作新型光纤光栅成为该领域的一个热点。结构调制型光纤光栅具有制备灵活、热稳定性好、无需载氢等特点,引起了该领域科研人员极大的兴趣。本文以结构调制型超长周期光纤光栅(SULPG)为切入点,从局域耦合模理论出发,建立了 SULPG的理论模型,在实验上完成了 SULPG的制备,对结构调制型超长周期光纤光栅的传感特性进行探讨。并在此基础上,基于熔拉技术提出了在锥形光纤上写制结构调制型超长周期π相移光纤光栅,结合调制型超长周期光纤光栅的特性构建了四种不同结构的模式干涉仪,利用光谱特性实现双参数的传感测量。论文的主要研究内容如下:1、基于局域耦合模理论,对SULPG的模式分布及传输特性进行分析,并详细的分析了直接拉锥型SULPG和锥上拉锥型SULPG的光谱特性,以及纤芯基模和包层模的耦合系数分布、折射率分布及模式分布随光纤几何形变区域的变化情况。2、利用熔融拉锥技术,完成了两种SULPG的写制,通过对光纤纤芯和包层几何结构周期性的调制形成光纤光栅,改变了以往光纤光栅只能在纤芯中形成的传统观念。此外,利用直接拉锥型SULPG和锥上拉锥型SULPG进行温度、应变、弯曲、扭转和折射率传感特性测试。通过对这两种结构的传感特性实验研究,可以通过减小锥形光纤的锥腰直径来提高外界环境的平均灵敏度。3、基于锥形光纤设计了具有较高温度和应变灵敏度的结构调制型超长周期π相移光纤光栅,制备工艺简单灵活,能够精确的控制引入相移的位置和长度。而且,利用此传感器的波长和幅值对温度和应变的不同响应,可以通过四种方式实现温度和应变的同时测量。基于结构调制型超长周期π相移光纤光栅进行双参数传感特性研究,测试不同应变变化下温度灵敏度,得到测试温度和应变交叉灵敏度相关性。4、基于结构调制型超长周期光纤光栅构成四种复合结构的模式干涉仪,首先分析了四种结构的形成机理,并利用四种复合结构分别实现了温度和应变的同时测量。根据所用仪器的规格,利用平均灵敏度系数计算出温度和应变的分辨率。
[Abstract]:With the rapid development of fiber grating manufacturing industry, the fabrication of novel fiber gratings has become a hot spot in this field. Structural modulation fiber gratings have the advantages of flexible fabrication, good thermal stability, no hydrogen carrier, etc. In this paper, based on the local coupling mode theory, the theoretical model of SULPG has been established, and the SULPG has been fabricated experimentally. The sensing characteristics of structurally modulated ultra-long period fiber gratings are discussed. Based on the fusing technique, a novel structure modulated type 蟺 phase shift fiber grating based on tapered fiber is proposed. Combined with the characteristics of modulated ultra-long period fiber grating, four kinds of mode interferometers with different structures are constructed, and the sensing measurement of two parameters is realized by using spectral characteristics. The main contents of this paper are as follows: 1, based on the local coupling mode theory, The mode distribution and transmission characteristics of SULPG are analyzed, and the spectral characteristics of direct tapered SULPG and tapered SULPG on cone are analyzed in detail, as well as the coupling coefficient distribution of core and cladding modes. The variation of refractive index distribution and mode distribution with the geometric deformation region of fiber. 2. Two kinds of SULPG writing systems are completed by using melt taping technique. The fiber gratings are formed by periodically modulating the fiber core and cladding geometry structure. The traditional idea that fiber Bragg gratings can only be formed in the core is changed. In addition, the temperature, strain and bending of the fiber grating are carried out by using the direct tapered SULPG and the tapered SULPG on the cone. Measurement of torsional and refractive index sensing properties. Experimental study on the sensing characteristics of these two structures, The average sensitivity of the external environment can be improved by reducing the tapered waist diameter of the tapered fiber. Based on the tapered fiber, a structured modulated ultra-long-period 蟺 phase-shifted fiber grating with high temperature and strain sensitivity is designed. The fabrication process is simple and flexible. The position and length of the phase shift can be precisely controlled. Furthermore, using the wavelength and amplitude of the sensor, different responses to temperature and strain can be obtained. The temperature and strain can be measured simultaneously in four ways. Based on the structural modulation type 蟺 -phase shifted fiber grating with extra long period, the two-parameter sensing characteristics are studied, and the temperature sensitivity under different strain changes is tested. The correlation between the cross sensitivity of temperature and strain is obtained. Based on the mode interferometer which is composed of four kinds of composite structures based on structurally modulated ultra-long period fiber gratings, the formation mechanism of the four structures is analyzed. The simultaneous measurement of temperature and strain is realized by using four kinds of composite structures, and the resolution of temperature and strain is calculated by using the average sensitivity coefficient according to the specifications of the instruments used.
【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TP212;TN253

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