设计了一种基于迈克尔逊干涉仪的光纤微流速传感器。传感器由单模光纤、双芯光纤、小球、高反膜构成。通过数值计算分析了双芯光纤长度、纤芯间距、小球半径和流体密度对传感器敏感度的影响。仿真结果表明, 光纤长度和小球半径的减小均能提高传感器的敏感度, 而双芯光纤的纤芯间距对敏感度的影响较小; 流体密度越大, 传感器的敏感度越小。计算结果显示, 传感器可以在较小尺寸的情况下实现超高灵敏度的流速测量。同时, 对不同设计参数下传感器输出的自由光谱范围进行理论推导与数值计算, 发现传感器各个参数与自由光谱范围成1/x或1/x1.5的关系。

A fiber-optic micro flow velocity sensor based on a Michelson interferometer is designed. The sensor consists of a single-mode fiber, a twin-core fiber, a small ball, and a high-reflection film. The effect of twin-core fiber length, core spacing, ball radius and fluid density on sensor sensitivity are analyzed by numerical calculation. The simulation results show that the shorter fiber length and smaller radius of the sphere can enhance the sensitivity of the sensor. The core spacing of twin-core fiber has less influence on the sensitivity. Larger density of the liquid leads to a higher sensitivity of the sensor. The calculations show that the sensor can achieve ultra-high sensitivity flow velocity measurement with small size. At the same time, the free spectral range of the sensor output under different design parameters is theoretically deduced and numerically calculated, and it is found that the relationship between each parameter of the sensor and the free spectral range was 1/x or 1/x1.5.