【作者】 张法；

【导师】 关柏鸥；

【作者基本信息】 大连理工大学 ， 光学工程， 2007， 硕士

【摘要】 光纤布拉格光栅(Fiber Bragg Grating—FBG)传感器由于具有波长编码测量、抗电磁干扰、抗腐蚀、结构简单、尺寸小等优点而被广泛地应用于传感领域。然而，由于FBG并不是一个永久性的结构，当长时间工作在高温环境下时FBG会消失或被“洗掉”。因此，FBG传感器一般只能适用于较低温度的环境。为了将其应用扩展到高温领域，急需研制耐高温光纤光栅。本论文采用高温退火工艺对特种掺杂光纤光栅进行热处理，利用杂质扩散效应造成纤芯中化学组分的空间周期性分布，由此形成纤芯折射率的空间周期性调制，成功地制作出化学组分光栅(chemical-composition grating—CCG)。由于其折射率调制是靠纤芯中化学组分的周期性分布形成的，因此这种光纤光栅具有极好的热稳定性，能够耐1000℃以上高温。在此基础上研究了CCG的温度响应和应变响应特性，研究了温度对CCG应变响应特性的影响。结果表明CCG在室温至1100℃范围内具有良好的温度响应特性，能够用于高温测量。CCG应变响应系数不随温度变化，其应变响应系数与普通光栅相当，能够满足高温热结构健康监测需要。由于CCG的反射率比较低，一般不超过20％，本文还探讨了提高CCG反射率的方法和途径，研究了氢气饱和度、初始光栅强度和紫外激光脉冲能量对CCG反射率的影响。结果表明：要提高CCG反射率，应尽可能地提高氢气饱和度和初始光栅强度，而且在写制初始光栅时应采用尽可能小的激光能量。上述结论对提高CCG反射率具有重要指导意义。更多还原

【Abstract】 Fiber Bragg grating (FBG) sensors have been widely used in sensing fields due to their distinguishing advantages, such as wavelength-encoded measurement, immunity to electromagnetic interference (EMI), light weight, simple for fabrication and so on. But FBG is not a permanent structure, it will be erased when operating for a long time under a sufficient high temperature. So they are only capable of operating in temperature range below 300℃. In order to extend FBG’s sensing applications at higher temperature regions, the sensors with high temperature sustainability should be fabricated.In this thesis we fabricated high-temperature-resistant chemical-composition gratings (CCGs) by writing FBGs in Ge/F codoped fiber with 193 nm eximer laser followed by special annealing procedure. The refractive index modulation of the CCGs is caused by a change in the chemical composition, hence these gratings show extremely high thermal stability at temperature up to 1100℃. The temperature and strain response of CCGs were investigated. The experimental results indicate that the temperature response of the CCGs has a fairly good performance. Further, the CCGs show strain coefficient that is about the same with normal FBGs. It is expected that the CCGs are suitable for health monitoring of the high temperature structure.In order to increase the reflectivity of the CCGs, we also investigated effects of hydrogen concentration, initial grating strength and UV laser pulse energy on the reflectivity of the CCGs. It is found that improving the initial grating reflectivity, enhancing the hydrogen concentration or using lower pulse energy in the initial grating inscription help to increase the reflectivity of the CCGs.更多还原