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。

Aiming at the problem of the high grating inscription scattering of previous microstructured optical fiber, inscription characteristics of a large side-hole microstructured optical fiber grating are analyzed by finite-difference time-domain method and the amalysis result is confirmed by finite element method. The large hole can be filled with fluid of suitable refractive index, the fluid-filled hole acting as a converging lens and the inscribing Gauss beam can focus into the core region, which improves grating inscription efficiency. The simulation results show that the inscription efficiency of the modified structure is 290% of conventional array hole photonic crystal fiber grating and 210% of single model fiber grating, respectively. An ultrahigh inscription efficiency and a relative less grating inscription scattering can be achieved, while the influence of inscription angle deviation is also discussed.