基于错位和无芯的高灵敏度及偏振调制光纤传感研究

发布时间：2018-03-19 23:26

本文选题：光纤传感技术　切入点：混合结构模式干涉　出处：《河南师范大学》2016年博士论文　论文类型：学位论文

【摘要】：光纤传感技术是以光波为载体,光纤为媒质,感知和传感外界被测量信号的新型传感技术。作为被测信号载体的光波和作为传播媒质的光纤,具有抗电磁干扰能力强、易为各种光电探测器件接收、方便光电转换以及适用于远程监测等优点。光纤传感技术的发展趋势是高灵敏度、高精度、多参数、同步在线、功能集成以及网络化等。本论文系统研究了包括干涉传感、激光传感、腔衰荡传感和偏振传感四种新型结构的光纤传感器的工作原理。并在分析上述传感器的理论基础上,对它们应用于温度、浓度和旋光角的测量进行了详细的实验探究,主要研究内容及创新成果包括以下几个方面。(1)在依据光纤中模式传播特性基本原理的基础上,对错位光纤、无芯光纤和法拉第旋镜组成的混合马泽-迈克尔逊结构的模式干涉和错位光纤传感结构不同位置处的电场分布进行理论建模分析,并进一步对干涉信号模式传播的数据进行拟合,深入比较和分析了使用法拉第旋镜消除光纤中的偏振态变化、补偿极化引起的信号衰减和消除外部扰动的原因和结果,为光纤混合干涉型传感技术应用于温度和浓度测量研究奠定了基础。(2)对混合马泽-迈克尔逊结构的模式干涉技术应用于温度和浓度测量进行了系统结构合理设置的实验研究。1)灵敏度增强型基于错位光纤的混合马泽-迈克尔逊干涉的温度传感系统。通过使用法拉第旋镜使光纤传感器具有较宽的应用测量范围,同时该系统可以有效地消除偏振状态随机变化带来的影响,提高了系统的灵敏度和稳定性。2)基于无芯光纤的多模干涉效应理论,实现了一个单模-无芯-单模-错位结构的温度自补偿的温度和浓度测量传感系统。所制备的单模-无芯-单模-错位传感部分最后通过检测反射的包层模波长漂移实现了对温度和液体浓度的测量,该系统的稳定性得到进一步提高。同时创新性的实验验证了无芯光纤对三种重金属溶液浓度的线性传感规律,为在一定范围内为检测重金属溶液浓度提供了一种有效的手段。对比分析了基于错位光纤的激光测温方法与FRM干涉测温方法,二者主要不同点在于错位光纤在激光测温系统中相当于滤波器,激光输出位置只选择在错位光纤干涉光谱的波峰处,因此,激光的中心波长将随着温度的变化而发生平移。实验对比结果表明,错位光纤的FRM干涉测温法灵敏度和稳定性均优于激光测温法。实现了对错位光纤温度传感系统和无芯错位光纤浓度传感系统测量数据的光谱分析和算法优化处理。分别利用改进BP神经网络和改进ELMAN神经网络实现了测量系统的数据分析和预测。给出了改进神经网络结构,详细分析了网络训练过程和参数的选取,最后分别对比说明了温度和浓度数据的预测值分析及误差分析,同时验证了该算法在光纤温度和浓度传感上的可行性,这也为错位光纤在压力、曲率等其他物理量传感上的精确测量提供了新思路。(3)提出了基于错位光纤的腔衰荡光谱技术的温度传感系统。根据朗伯-比尔定律理论分析了环腔损耗及衰荡时间与错位传感部分随温度变化的关系,错位量的变化和由温度引起的错位长度的变化最终可以通过测量衰荡时间检测出来,该系统改进了光谱解调方式并简化了信号的采集处理过程。实验结果表明,当选择不同错位量时,通过曲线拟合获得了衰荡时间τ和错位量D之间的关系,错位量对衰荡输出波形有较大的影响。若输入光功率足够大,错位光纤的引入使腔内总损耗增加从而导致衰荡时间明显减少。(4)针对现有干涉型浓度传感系统存在的测量精度不高和解调困难等问题,提出了一种新型两级调制的磁致旋光角和浓度的偏振测量传感系统。这种技术将传统的直流调制磁光检测技术与交流调制磁光检测技术相结合,去除了纯交流调制产生的磁旋光角变化引起的误差。设计实现了脉冲宽度调制控制的交直流调制信号源。实验验证了掺铽(Tb~(3+))光纤可以用于交直流调制旋光溶液浓度测量系统,该系统采用包括对准装置在内的全光纤链路,使传感设备更便携和紧凑。
[Abstract]:Optical fiber sensing technology is to light as the carrier and optical fiber as the medium, the new sensor technology and sensor sensing the measured signal. As the external optical signal measured by carrier and optical fiber as a communication medium, has the strong ability of anti electromagnetic interference, easy for a variety of photoelectric detector receiver, photoelectric conversion and convenient for remote monitoring etc.. The development trend of optical fiber sensing technology is of high sensitivity, high precision synchronous on-line, multi parameter, function, integration and network. This thesis has studied including interferometric sensing, laser sensor, the working principle of cavity ring down sensor and optical fiber sensing polarization of four kinds of new structure. And in the theoretical basis of the analysis of the sensor on the use of them in measuring temperature, concentration and rotation angle were studied with experiments, the main research contents and innovations include the following aspects. (1) in accordance with the According to the basic principle of the mode propagation characteristics in optical fiber, optical fiber of dislocation and dislocation, the electric field distribution mode interference optical fiber sensing structure at different locations without mixing Ma Ze Michelson structure and core fiber Faraday rotator mirror the theoretical modeling and analysis, and further to fit the interference signal model of communication data. Further comparison and analysis of the use of the Faraday rotation mirror to eliminate the polarization variation in the optical fiber, and eliminate the cause and result of external disturbance compensation signal attenuation due to polarization, optical fiber sensing technology in the application of mixing type of measurement of temperature and concentration of the foundation. (2) of the mixed Ma Ze Michelson structure mode interference technology the application experiments were conducted to study the system structure of.1 in the measurement of temperature and concentration) sensitivity enhanced fiber mixed dislocation interference based on Ma Ze Michelson The temperature sensing system. With the application of a wide measurement range by using Faraday rotation mirror to make optical fiber sensor, and the system can effectively eliminate the influence of random polarization state changes, improve the sensitivity and stability of.2 system) multimode non core fiber interference effect theory based on the implementation of a single - core single mode - dislocation structure temperature self compensation of temperature and concentration measurement sensor system. The prepared single - core single-mode - no dislocation sensing part finally realized the measurement of temperature and concentration of liquid through the cladding mode wavelength shift detection of reflection, the stability of the system has been further improved. At the same time, innovative experiment the experiments show that the linear sensing rules of three kinds of heavy metal concentration in the core optical fiber, for a certain range of concentration detection of heavy metal solution provides an effective means of comparative analysis. With the method of FRM laser temperature measurement method based on optical fiber displacement interference thermometry, the two main difference lies in the dislocation of optical fiber in laser measurement system is equivalent to the filter, select only the crest, spectral interference in the fiber laser output position so the dislocation, the center wavelength of the laser will change with temperature. The experimental results show that the translation optical fiber FRM interferometer, dislocation temperature sensitivity and stability are better than the laser temperature measurement method. The spectrum of misalignment of optical fiber temperature sensing system and non core optical fiber sensing system for measuring dislocation concentration data analysis and algorithm optimization. Using the improved BP neural network and the measurement system of data analysis and prediction of improved ELMAN neural the network is given. An improved neural network structure, a detailed analysis of the selected network training process and parameters, finally, in contrast to the temperature and concentration Analysis and error analysis of data value prediction, and verifies the feasibility of the algorithm in optical fiber sensing the temperature and concentration, which also misplaced fiber in pressure, provides a new idea for accurate measurement of curvature and other physical quantity sensor. (3) proposed the temperature sensing system down spectroscopy optical fiber cavity ring dislocation based on the Lambert law. According to the Bill theory to analyze the ring cavity loss and relation ring down time and displacement sensing part varies with temperature, change of displacement and temperature caused by dislocation length can eventually by measuring the ringdown time detecting, the system improves the spectrum demodulation and simplifies the acquisition process signal. The experimental results show that when choosing different displacement, obtained by curve fitting the relationship between the ringdown time and offset D, offset of the ring down have a greater impact on the output waveform. If the input optical power is large enough, the dislocation of the optical fiber so that total loss resulting in increased cavity ringdown time was significantly reduced. (4) to improve the measurement accuracy of the existing interferometric sensing system of density is not high and the demodulation difficulty, proposed polarization measurement sensor system Faraday angle and the concentration of a new two stage modulation. This technique will direct modulation magnetic detection technology and traditional optical communication optical modulation magnetic detection technology combining magnetic rotation error caused by pure AC modulation produced by angle removal. The design and implementation of pulse width modulation control of DC modulation signal source. Experimental verification of terbium doped fiber (Tb~ (3+)) can be used to make optical modulation solution concentration measurement system of DC, the system uses optical fiber link including the alignment device, the sensing device is more portable and compact.

【学位授予单位】：河南师范大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TP212

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