木堆结构光子晶体最佳参量的理论分析

Theoretical analysis of optimum parameters for woodpile-type photonic crystals

为了优化3维木堆结构光子晶体的结构参量,采用平面波展开法,从高度和周期之比、填充率、晶格与 x 轴的夹角3方面理论分析了3维木堆结构光子晶体完全禁带的性质。当填充率在0.25～0.3之间变化时,带隙比变化很小。最佳高度和周期之比为1.3。当晶格与 x 轴的夹角在40°～50°之间变化时,带隙比超过0.18。当高度和周期之比等于1.3,旋转角度在42°～48°之间变化时,最大带隙比为0.2保持不变。结果表明,3维木堆结构光子晶体的结构参量调节范围比较宽。这一结果为实验室制备带来方便。

In order to optimize the structure parameters of 3-D woodpile-type photonic crystals, based on the plane-wave method, the property of complete forbidden bands of woodpile structure was theoretically studied in terms of varying aspect heightto-pitch ratios ,filling fractions, and rotation angles. It was found that the gap to midgap ratio changed slightly with a filling fraction ranging from 0.25 to 0.30. The optimum height-to-pitch ratio was about 1.3. The gap to midgap ratio became larger than 0. 18 when the rotation angle changed from 40° to 50°and the maximum gap to midgap ratio of 0.2 remained unchanged for the rotation angle ranging from 42° to 48° with height-to-pitch ratio of 1.3. The results show this type of woodpile structure can produce big band gaps in a wider parameter range, which offers convenience for preparing threedimension photonic crystals in laboratory.