提出了一种基于多模干涉效应(MMI)的单模-多模-间隙-单模（SMGS）光纤悬臂梁振动传感器。采用光束传播法（BPM）对这种结构的光传输性能进行数值模拟，并通过有限元分析方法对光纤悬臂梁进行了振动模态分析，从理论上优化设计了该类光纤振动传感结构。在实验上制备了长度为22 mm的悬臂梁结构，详细研究了多模区光纤的长度对声频振动响应的影响。实验结果表明，该SMGS振动传感器在130 Hz时响应效果最好，对应的声压灵敏度为4 mV/mPa，线性相关系数为0.9962，线性度和可重复性良好，并且实验结果和理论模拟结果相符合。这种光纤振动传感器具有制备工艺简单、成本较低和灵敏度高等特点，有望应用于对某些具有特殊振动频率点的远距离振动传感。

A kind of novel fiber cantilever vibration sensor with the structure of single mode-multimode-gap-single mode (SMGS) fiber is proposed based on the effect of multimode interference. The beam propagation method (BPM) is adopted to simulate the light propagation in the fibers. The finite element model of the cantilever is established in order to analyze the vibration characteristics of the optic-fiber cantilever, and the optimal design of this kind of fiber vibration sensors is conducted in theory. In the experiments, the fiber cantilevers with the length of 22 mm are fabricated by four different lengths of multimode fibers. The characteristics of cantilevers vibration with different lengths of multimode fibers are analyzed in details. The experimental results agree well with the theoretical simulation results. It shows that the proposed SMGS sensor has the maximum sensitivity of 4 mV/mPa at the frequency point of 130 kHz and the linear correlation coefficient of 0.9962. The experimental results indicate that this kind of sensor has a linear response and good repeatability within given sound pressure level. The proposed sensor maintains the advantages of easy-preparation, low-cost and high-sensitivity, which is expected to be applied to the field of the remote vibration sensing of some special resonance frequency points.