大小周期正方格子复合结构的光子带隙特性

把具有宽完全带隙的粗锐复合的周期常数为a的二维正方格子再与周期常数为a₂的大周期简单正方格子复合，发现大周期正方格子起缺陷作用.并发现当a₂<5a时,缺陷态明显地随入射角度变化.此变化随a₂的增大而减少.用FDTD方法计算了其透射和反射谱,结果表明缺陷峰透射率与a₂的大小成反比.另外还发现: 缺陷峰结构与大周期正方格子的圆柱直径的关系曲线与a₂关系不大.通过调节大周期正方格子的圆柱的直径，可获得单关键词：光子晶体光子能隙复式结构缺陷态

Band gap characteristics of compound structure composed of lattices with different periodic constants

Our numerical simulation results show that if a compound structure is composed of a lattice with a larger periodic constant and a lattice with a small periodic constant, the lattice with larger periodic constant will play the role of defects. The frequencies of defect modes are dependent on the rod radius (r₂) of square lattice with a larger periodic constant, and the relationship of the defect modes and r₂ is almost independent of a₂. The defect mode is dependent on incidence angle when a₂<5a. The dependence of defect mode on incidence angle decreases with the increasing of a₂. Furthermore, by optimizing the size of the rods (r₂) of the larger periodic lattice, single defect mode, multiple defect modes with equal or different frequency spacing, including single polarization or TE and TM overlap defect mode, can be gotten respectively. The transmissivity of the defect modes are inversely proportional to a₂.