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FBG的制作及其压力传感研究
Study on the Fabrication of Fiber Bragg Gratings and Application in Pressure Sensor
【作者】 张金；
【导师】 张玉书；
【作者基本信息】 大连理工大学 ， 微电子与固体电子学， 2008， 硕士
【摘要】 光纤Bragg光栅（FBG）是沿光纤轴向在光纤内形成周期性折射率调制分布的一种新型光纤无源器件,由于其在光纤通信和传感领域有广泛的应用前景,因此受到高度重视。其中,FBG因具有高灵敏度、体积小、抗电磁干扰、波长编码、易于阵列等优点,已成为目前最具有发展前途的光纤传感器件之一。利用FBG传感器实现恶劣条件下的高温高压参数的测量是目前光纤传感领域的研究热点。本文在阐述FBG的模式理论和传感原理的基础上,根据实验室现有条件,对普通单模石英光纤进行了掺氢处理,利用相位掩模法制作了FBG。通过实验研究了激光脉冲能量、脉冲频率、曝光时间和退火对FBG写入的影响,得到了利用相位掩模和紫外写入技术制备FBG的最佳工艺条件,并对所制作的FBG进行了温度和应变特性分析。利用弹性应变筒原理,设计了用于高温高压测量的、投入式的、双层金属筒式结构的FBG压力传感头。并使用有限元分析软件ANSYS,对使用四种不同材料(高弹性不锈钢1Cr18Ni9、低碳钢Q235、铜、铝)、不同结构尺寸（壁厚分别为1.0mm和1.5mm）制作的薄壁筒在均匀分布压力下的受力和形变进行了仿真分析,验证了结构设计的合理性。通过计算得出,采用不锈钢1Cr18Ni9材料制备的应变筒所能承受的最大压力理论上达到63Mpa。利用参考光栅法有效解决了交叉敏感问题。实验测得传感器的压力测量范围为0～42Mpa,温度20℃～230℃,压力灵敏度、线性度和重复性良好,达到了项目的设计要求。为了解决FBG与传感结构的有效结合,实现高温下压力参数的稳定测量,本文采用了金属化封装的光栅进行测试研究,得到了理想的测量结果。
【Abstract】 Fiber Bragg grating （FBG） is a new type passive optical component with the refractive index modulated along the fiber length. Recently FBG has become a very important component for optical sensing devices considering its many merits such as high sensitivity, light weight, small size, easily array and wavelength encoded, and it has become one of the most promising optical device. However, because of the low pressure sensitivity of bare FBG and its sensitive simultaneity of both temperature and strain, bare FBG cannot be directly used in sensing area, and the application in harsh environments （high temperature and high pressure） with high resolution and sensitivity remains a big challenge.FBG was fabricated on hydrogen loaded single mode optical fiber. The optimal fabrication parameters were concluded by considering the affect of the laser power, frequency and exposure time.Based on full analysis of bare FBG characteristics, a thin-wall cylinder pressure sensor has been designed and fabricated, which can be used in the measurement of high temperature and high pressure environment. By using ANSYS software, the strain characteristics of the cylinder （made of four different kinds of material and in different sizes） were calculated. The most theoretical result of pressure for stainless steel material 1Cr18Ni9 is 63MPa. The measurement ranges of actual pressure and temperature are 0～42MPa and 20℃～230℃, respectively. Meanwhile, because of the reference FBG, cross-sensitivity of pressure and temperature is solved effectively.In order to achieve the most effective integration between FBG and sensor devices, and the steady result in high-temperature environment measurement, metal-coated FBG （MFBG） is has been used in pressure sensor, which brought a better result.