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 properties of two-dimensional square lattice photonic crystal waveguide were discussed using plane wave expansion method. By reducing the radius of a row column to half of the original value, the maximum group velocity of 0.066c and 0.083c were obtained, corresponding to the bandwidth of 0.060(ωa/2πc)and 0.062(ωa/2πc), respectively. This indicates that photonic crystal waveguide with better slow-light characteristics can be obtained by reducing the radius of a row column. It is found that the guide mode curve moves to lower frequency with the increase of defect column radius (within medium column radius), and smoothes gradually, namely group velocity decrease. The study will provide a theoretical basis for the optimization of square lattice photonic crystal slow-light waveguides.