针对传统微结构光纤光栅写入过程中的写入散射大的问题,采用时域有限差分法分析了大圆孔微结构光纤光栅的写入场分布特性,并用有限元法验证了分析结果。提出将适当折射率的流体填充至大圆孔区域,利用柱形流体的微透镜效应会聚高斯光能量至纤芯掺杂区域,从而改善写入效率。仿真结果表明改进后的光纤光栅写入效率分别是周期性光子晶体光纤光栅和单模光纤光栅写入效率的290%和210%左右,可以提高光纤光栅的写入效率,降低散射损耗。此外,还针对高斯光束写入角度误差对写入效率的影响进行了初步分析。 In order to solve the problem of large write scattering in the traditional microstructure fiber gratings, the write field distribution characteristics of the microstructured fiber gratings with large circular holes were analyzed by finite difference time domain (FDTD) method. The finite element method was used to verify the analysis results. It is proposed to fill the area of ​​the large circular hole with a fluid of suitable refractive index and to utilize the micro-lens effect of the cylindrical fluid to converge the Gaussian optical energy into the doped region of the core to improve the writing efficiency. The simulation results show that the improved write efficiency of the FBG is about 290% and 210% of the write efficiency of the periodic PCF and SMF respectively, which can improve the write efficiency of the FBG and reduce the scattering loss. In addition, a preliminary analysis of the effect of the write angle error on the write efficiency is also given.