针对裸光纤光栅在声波作用下的应变灵敏度过低导致难以检测到有效反射波长变化的问题，文章提出以光纤光栅纵向传感为模型，并在光栅周围涂上一层厚度远超光纤内径的低杨氏模量圆柱状涂覆层，以增加光纤光栅的应变灵敏度，并用相移光栅反射谱的线性区作为边缘滤波法边缘来提高激光检测的灵敏度，利用传输矩阵法仿真分析光栅反射谱及激光反射率曲线。仿真结果表明，声波纵向传感模型的应变灵敏度要优于横向传感模型，且低杨氏模量的涂覆层可以显著提高光栅的应变灵敏度，在频率低于1.7 kHz的声波作用下，涂有聚氨酯涂覆层的光纤光栅纵向传感灵敏度达到了6.1 nm/MPa，是裸光纤光栅的381倍，结合相移光栅反射谱线性区综合灵敏度提升2 203.6倍，有效地提升了光纤光栅在声波检测方面的灵敏度。

The strain sensitivity of bare fiber grating under the action of acoustic wave is too low, which is difficult to detect the effective reflection wavelength change. In this paper, the longitudinal sensing of fiber grating is used as a model, and a layer of thickness far exceeding the inner diameter of the fiber is coated around the grating. Low Young's modulus cylindrical coating is used to increase the strain sensitivity of the fiber grating. We also use the linear region of the reflection spectrum of the phase-shift grating as the edge of the edge filtering method to improve the sensitivity of laser detection. Transmission matrix method is then applied in the simulation to analysis the reflection spectrum of grating and reflectance curve of laser. The simulation results show that the strain sensitivity of the longitudinal sensing model of acoustic wave is better than that of the transverse sensing model. The coating layer with low Young's modulus can significantly improve the strain sensitivity of the grating. Under the action of acoustic wave with frequency lower than 1.7 kHz.The longitudinal sensing sensitivity of the fiber grating coated with polyurethane coating reaches 6.1 nm/MPa, which is 381 times higher than that of the bare fiber grating. Combined with the phase-shift grating reflection spectrum linear region, the comprehensive sensitivity is improved by 2 203.6 times, effectively improving the acoustic wave detection sensitivity of the grating.