新型光纤布拉格光栅传感器研究
发布时间：2019-04-25 22:41
【摘要】：在石油工业和油气田勘探开发领域中,研制新型光纤传感器,建立完整的光纤传感网络系统,实时监测温度、压力、振动等诸多地质物理量,对于油气藏精细描述,提高油气资源勘探开发效率十分重要。然而,光纤传感器目前仍面临着集成化、多参量测量以及系统的分布式、网络化传感等诸多方面的挑战。基于光纤布拉格光栅(Fiber Bragg Grating, FBG)波长编码型的光纤传感器,具有体积小、重量轻、抗电磁性、远距离传输能力和抗腐蚀性等优点,并且具备波长可复用性和多参量敏感性,在分布式传感领域具备极强的优势和广泛的应用前景。本论文研究了新型光纤FBG的传感机理,研制了多种新型光纤FBG传感器,对每种传感器的制作原理、传感特性做了深入研究。具体研究内容包括：1.概述了光纤波导和光纤FBG的模式耦合理论,对比了几种非对称结构的光纤FBG,包括倾斜光纤FBG、长周期光纤FBG和局部写入光纤FBG等,介绍了几种常用的FBG刻写技术；2.研制了三种基于“传感结构的特殊设计”的标准FBG弯曲、振动传感器。(1)制作了一种基于组合式杠杆结构的双FBG光纤加速度传感器。两只FBG沿着杆上下对称固定。当感受到外界振动时其布拉格波长沿相反方向偏移。实验测试结果显示由于等截面量具有极强的横向抗干扰能力,再加上L型刚性杠杆可实现外界振动信号的有效放大,测得该传感器的静态弯曲灵敏度为4.58nm/mm,动态灵敏度高达218.4pm/G。(2)利用金属波纹管的高弹性,制作了一种芯轴式的FBG三维加速度传感器,将质量块位于三维空间的中心位置,利用弹性金属波纹管沿质量块各个面对称固定,作为FBG与质量块连接的缓冲介质。测试过程中对其中三只位于不同轴向的光纤FBG耦合输出至检测元件,验证了传感器对三维空间振动的方向依赖性。(3)研制了一种基于弯曲非等截面梁的光纤FBG传感器,用一个半孔型的梁作为弯曲结构,其自由端用作惯性质量块来感受外界沿纵轴的位移和振动。经过模拟得到半孔梁的应变沿轴向为非均匀线性增加,因此随着形变量的增加在其表面的FBG实现了布拉格(Bragg)光谱展宽和峰值波长的漂移。实验中通过对光谱功率和峰值波长同时检测,得到了其纵向弯曲和温度的区分灵敏度分别为1.9dBm/mm和11.85pm/℃。进一步测试了传感器的振动响应,得到该传感器的共振频率为250Hz,振动响应范围为0到3.5G。3.基于“光栅结构的特殊设计”,利用紫外曝光技术写制了一种新型的离轴型单模光纤光栅。写栅过程中将光纤平行偏移激光光路一定程度使得照射在光纤上的衍射条纹沿光栅横截面为部分曝光。制成的离轴FBG包层模式被有效耦合出纤芯,其中一些低阶包层模式对弯曲具有方向相关性。利用离轴FBG作为全光纤型弯曲传感器,实现了二维空间的矢量测量。弯曲灵敏度最高可达1.25dB/m~(-1),曲率范围为0到lm~(-1)。并分别测量了弯曲传感器对周围环境的温度和折射率交叉灵敏度,验证了传感器的温度、折射率不相关性。4.通过对倾斜光纤FBG (Tilted FBG, TFBG)传输光谱中的共振模式加以理论分析和软件模拟,制作了两种基于TFBG的全光纤型传感器。(1)刻写了两只倾斜角度为2° TFBG, Bragg波峰距离控制为20nm有利于在光谱透射窗口中同时检测到各TFBG的共振谱信息。利用这两只TFBG制作成一个三维形变光纤传感器。传感器的空间形变测试结果表明,在弯曲曲率从0m~(-1)到3m~(-1)范围内,可实现空间的弯曲定标测量(弯曲不确定为士180°)。弯曲灵敏度依据方向不同从-0.33dB/m~(-1)变化至+0.21dB/m~(-1)。第三维方向的轴向应变灵敏度为1.06pm/με。且沿轴向的第三维空间可通过应变和温度波长区分测量。该传感器结构紧凑,总长度少于3cmm,且实现了三维空间的一体式测量。(2)讨论了表面等离子体共振(SPR)传感器的原理和传感特点及TFBG镀膜激发SPR的优点。基于TFBG的光栅倾斜平面的方向性以及模拟所得的具有等离子体特性的高阶包层模的模场能量分布特性,设计了一种更为简单的TFBG镀膜方式,优化了光栅表面SPR的耦合效率。对传感器在盐溶液中的响应加以验证,并进一步在微小折射率扰动溶液中测量SPR共振峰处的能量变化,通过能量差分运算得到折射率灵敏度高达3.34×10~4dB/RIU。结果表明,通过定向单面涂覆金层可实现SPR的高效率激发,大大降低SPR传感器的制作的复杂性。
[Abstract]:In the field of petroleum industry and oil and gas field exploration and development, a new type of optical fiber sensor is developed, and a complete optical fiber sensing network system is established to monitor the temperature, pressure, vibration and other geological physical quantities in real time. It is very important for the fine description of oil and gas reservoirs and to improve the exploration and development efficiency of oil and gas resources. However, the optical fiber sensor is still facing the challenges of integration, multi-parameter measurement and distributed and networked sensing of the system. The optical fiber sensor based on the fiber Bragg grating (FBG) wavelength coding type has the advantages of small volume, light weight, electromagnetic resistance, long-distance transmission capability and corrosion resistance and the like, And has strong advantages and wide application prospect in the field of distributed sensing. In this paper, the sensing mechanism of a new type of FBG is studied, and a variety of new FBG sensors are developed. The manufacturing principle and the sensing characteristics of each sensor are deeply studied. The specific research contents include:1. In this paper, the mode-coupling theory of the fiber-optic waveguide and the fiber-optic fiber Bragg fiber (FBG) is summarized, and the optical fiber FBG of several asymmetric structures is compared, including the oblique optical fiber FBG, the long-period fiber FBG and the local write-in fiber FBG, etc., and several commonly used FBG etching techniques are introduced. Three "The special design of the sensing structure"-based standard FBG bending and vibration sensors have been developed. (1) a dual FBG fiber acceleration sensor based on a combined lever structure is manufactured. The two fbg are symmetrically fixed along the upper and lower sides of the rod. The bragg wavelength is offset in the opposite direction when the outside vibration is felt. The results show that the static bending sensitivity of the sensor is 4.58 nm/ mm and the dynamic sensitivity is up to 218.4 pm/ G. And (2) using the high elasticity of the metal corrugated pipe, a core shaft type FBG three-dimensional acceleration sensor is manufactured, the mass block is positioned in the center position of the three-dimensional space, and the elastic metal corrugated pipe is fixed along each surface of the mass block and is used as a buffer medium for connecting the FBG and the mass block. In the test, three optical fiber FBG sensors, which are located in different axial directions, are coupled and output to the detection element, and the direction dependence of the sensor on the three-dimensional space vibration is verified. (3) An optical fiber FBG sensor based on a curved non-uniform cross-section beam is developed, and a half-pass beam is used as a bending structure, and the free end of the beam is used as an inertia mass block to sense the displacement and vibration of the outside along the longitudinal axis. The strain of the semi-porous beam is increased linearly in the axial direction through the simulation, so the Bragg (Bragg) spectral broadening and the peak wavelength shift are realized with the increase of the shape variable on the surface of the FBG. By simultaneous detection of the spectral power and the peak wavelength, the sensitivity of the longitudinal bending and the temperature was 1.9 dBm/ mm and 11.85 pm/ 鈩，
本文编号：2465530
[Abstract]:In the field of petroleum industry and oil and gas field exploration and development, a new type of optical fiber sensor is developed, and a complete optical fiber sensing network system is established to monitor the temperature, pressure, vibration and other geological physical quantities in real time. It is very important for the fine description of oil and gas reservoirs and to improve the exploration and development efficiency of oil and gas resources. However, the optical fiber sensor is still facing the challenges of integration, multi-parameter measurement and distributed and networked sensing of the system. The optical fiber sensor based on the fiber Bragg grating (FBG) wavelength coding type has the advantages of small volume, light weight, electromagnetic resistance, long-distance transmission capability and corrosion resistance and the like, And has strong advantages and wide application prospect in the field of distributed sensing. In this paper, the sensing mechanism of a new type of FBG is studied, and a variety of new FBG sensors are developed. The manufacturing principle and the sensing characteristics of each sensor are deeply studied. The specific research contents include:1. In this paper, the mode-coupling theory of the fiber-optic waveguide and the fiber-optic fiber Bragg fiber (FBG) is summarized, and the optical fiber FBG of several asymmetric structures is compared, including the oblique optical fiber FBG, the long-period fiber FBG and the local write-in fiber FBG, etc., and several commonly used FBG etching techniques are introduced. Three "The special design of the sensing structure"-based standard FBG bending and vibration sensors have been developed. (1) a dual FBG fiber acceleration sensor based on a combined lever structure is manufactured. The two fbg are symmetrically fixed along the upper and lower sides of the rod. The bragg wavelength is offset in the opposite direction when the outside vibration is felt. The results show that the static bending sensitivity of the sensor is 4.58 nm/ mm and the dynamic sensitivity is up to 218.4 pm/ G. And (2) using the high elasticity of the metal corrugated pipe, a core shaft type FBG three-dimensional acceleration sensor is manufactured, the mass block is positioned in the center position of the three-dimensional space, and the elastic metal corrugated pipe is fixed along each surface of the mass block and is used as a buffer medium for connecting the FBG and the mass block. In the test, three optical fiber FBG sensors, which are located in different axial directions, are coupled and output to the detection element, and the direction dependence of the sensor on the three-dimensional space vibration is verified. (3) An optical fiber FBG sensor based on a curved non-uniform cross-section beam is developed, and a half-pass beam is used as a bending structure, and the free end of the beam is used as an inertia mass block to sense the displacement and vibration of the outside along the longitudinal axis. The strain of the semi-porous beam is increased linearly in the axial direction through the simulation, so the Bragg (Bragg) spectral broadening and the peak wavelength shift are realized with the increase of the shape variable on the surface of the FBG. By simultaneous detection of the spectral power and the peak wavelength, the sensitivity of the longitudinal bending and the temperature was 1.9 dBm/ mm and 11.85 pm/ 鈩，
本文编号：2465530
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