为解决传统胶封传感器普遍存在的蠕变、老化问题,本文提出基于一步超声法的光纤光栅表面金属化封装方法。在相同条件下分别对有聚酰亚胺涂覆层和无涂层的两种FBG进行金属化封装，研究了封装后FBG传感器的光谱、热学和力学特性，并利用扫描电子显微镜对其横截面的微观形貌进行了表征。结果表明: 封装后有涂覆层FBG的反射光谱无明显畸变、边模抑制比大于10 dB，温度灵敏系数达34.63 pm/℃，应变灵敏系数为1.18 pm/με，应变传递效率达98.5 %，线性度达0.999，均优于无涂层的FBG传感器。当温度从14.2 ℃突变到80 ℃经过多次冲击试验，发现金属化封装无涂层的FBG的温度增敏结构被破坏，而有涂层的FBG传感器仍保持优异的温度响应特性。SEM图显示，金属合金与有无涂覆层的光纤和金属基底都结合致密。该方法无需对光纤进行表面金属化预处理，操作简单易行，在恶劣环境、超长服役时间的光纤传感应用领域中具有重要的价值。

A one-step ultrasonic welding approach for metal-packaged fiber Bragg grating (FBG) sensors was proposed to solve the problem of aging and creep in the field of traditional adhesive packaging. FBGs with and without polyimide coatings were bonded to the surface of an aluminum alloy substrate via one-step ultrasonic welding. The spectrum and thermal and mechanical properties of the bonded FBGs were studied. Additionally, the cross sections of the FBG sensors were analyzed by a Scanning Electron Microscope (SEM). The results reveal that the reflection spectrum of the coated FBG sensor has no obvious distortion, and the side-mode suppression ratio is higher than 10 dB. It is shown that the temperature sensitivity coefficient of the polyimide-coated FBG is 34.63 pm/°C, the strain sensitivity coefficient is 1.18 pm/με, the strain transfer efficiency is 98.5%, and the linearity reaches 0.999, the value of which is higher than that of the uncoated FBG sensor. After performing several repetitive temperature impact tests at temperatures ranging from 14.2 °C to 80 °C, it is found that the uncoated metal-packaged FBG sensor is destroyed, whereas the coated sensor maintains excellent temperature response characteristics. The SEM results show that the metal alloy bonded well to the surface of the coated and uncoated optical fibers. Furthermore, the one-step ultrasonic welding technique was confirmed to not require metallic pretreatment on the FBG surface; thus, the technique is relatively simple and requires less time to implement. The results indicate that the polyimide coating can effectively improve the reliability of metal-packaged FBG sensors for measuring temperature and strain, which would be useful in rigid-environments and for long-term sensing.