基于Michelson干涉仪的高灵敏度光纤高温探针传感器

提出了一种简单的高灵敏度的光纤高温探针传感器, 该传感器由一小段多模光纤和一端镀有银膜的单模光纤熔接而成. 由于单模光纤和多模光纤的纤芯直径不同, 当光波从多模光纤传输至多模光纤和单模光纤的熔接端面时, 一部分纤芯光耦合进包层, 因为单模光纤纤芯的折射率和包层的折射率不同, 不同模式的光经过银膜反射后在多模光纤内重新耦合进单模光纤, 最终形成干涉.随着外界温度的升高, 干涉谱峰值会向长波方向漂移. 实验结果证明这种传感器在470 ℃–600 ℃范围内具有很好的稳定性, 线性度达99.7%, 灵敏度为120 pm/℃, 可作为远距离反射型探针温度传感器, 在石油探测和油气田开发等领域有着广泛的应用前景. 关键词： 光纤传感 温度测量 Michelson干涉

High temperature probe sensor with high sensitivity based on Michelson interferometer

We propose a high sensitivity fiber optical temperature sensor with simple structure. The sensor is composed of a multimode fiber (MMF) and a short single mode fiber (SMF) whose end is coated with silver film as a reflective mirror. Due to the mismatch between the MMF core and the SMF core, part of guided mode is coupled with the cladding modes of downstream SMF cladding. The mode index difference between the fiber core and cladding is attributed to the phase difference, resulting in interference. When ambient temperature increases, the interference spectrum presents red-drift because of the difference in thermo-dependence. A high temperature sensitivity of 120 pm/℃ is achieved, and the linearity is 99.5%. The configuration is simple and has a compact size, making it a good candidate for distant temperature sensing and oil prospecting.
Keywords： fiber sensor temperature measurement Michelson interferometer