针对一种圆形晶格微结构光纤，采用有限差分波束传播法对多孔光纤的模式双折射特性进行数值模拟。通过分析横截面结构参数的变化对模式双折射的影响，得到了合适的光纤结构参数，其偏振拍长可以在1310 nm附近较宽的波长范围内基本保持稳定，工作带宽可达200 nm，具有较好的消色差特性。这种结构的光纤适合制作宽带稳定的消色差波片。

For a round lattice micro-structure optical fiber, the birefringence properties are simulated by the finite difference beam propagation method. After analyzing the influence of different cross-section structure parameters on birefringence, we obtain an appropriate set of structure parameters. With these parameters, the polarization beat length remains stable in a wide wavelength range near the 1310 nm communication window, and the working bandwidth can reach 200 nm, so it has a better achromatic characteristic. The fiber is suitable for making wideband achromatic plate.