利用平面波展开法对二维正方晶格光子晶体波导进行了理论研究和分析。通过减小一排介质柱半径至原来的一半以及直接去除一排介质柱分别获得了0.066c和0.083c的最大群速度,对应的带宽分别为0.060(ωa/2πc)和0.062(ωa/2πc),得出了通过减小介质柱的半径比去除一排介质柱可获得更优慢光效果的结论。进一步分析了缺陷柱半径的变化对导模色散曲线及群折射率曲线的影响,发现当缺陷柱半径在低于介质柱半径的范围内变化时,导模曲线随着缺陷柱半径的增加而向低频方向移动,且渐趋平坦,亦即群速度变小。研究结果对优化正方晶格光子晶体慢光波导提供了理论依据。 The planar wave expansion method is used to study and analyze the theory of two-dimensional square lattice photonic crystal waveguide. The maximum group velocities of 0.066c and 0.083c were obtained by decreasing the radius of a row of dielectric columns to the original half and removing a row of dielectric columns directly. The corresponding bandwidths were 0.060 (ωa / 2πc) and 0.062 (ωa / 2πc) It is concluded that the optimal slow-light effect can be obtained by reducing the radius of the dielectric column than by removing a row of dielectric columns. The influence of the variation of defect column radius on the dispersion curve and the index of refraction of the guided mode is further analyzed. It is found that when the radius of the defect column changes in a range below the radius of the column, the guide curve changes with the increase of the radius of the defect column Low frequency direction of movement, and gradually flat, that is, the group velocity becomes smaller. The results provide a theoretical basis for optimizing slow-waveguides of tetragonal lattice photonic crystals.