光子晶体局域缺陷模及耦合特性研究

用超胞平面波展开法计算了二维正方格子介质柱光子晶体缺陷模，系统模拟了在改变缺陷模数目和缺陷模之间的距离及在不同耦合方向等情况下的耦合特性。计算结果表明：局域缺陷模之间的耦合所产生分裂的缺陷模式频率随着缺陷之间的距离而发生变化．当缺陷之间距离增加时，缺陷模之间耦合变得越来越弱且奇模和偶模交替变化；随着耦合缺陷点数目增加，缺陷模在光子带隙内形成一个缺陷带；当平面波平行于缺陷模耦合方向入射时．可以同时激发奇模和偶模．当入射平面波垂直于耦合方向时．仅产生偶模；沿对角线方向耦合的定域化的缺陷模电磁场快速衰减使得那些方向每一个单谐振腔局域光场与它邻近的谐振腔不发生耦合，其本征频率与波矢无关。

The Study of the Defect Modes and Coupling Characteristics of Photonic Crystals

The defect modes in two-dimensional square dielectric photonic crystals have been calculated, and the coupling characteristics of the defect modes of point defects have been simulated systematicly when the numbers of defects, the distance between two defects and the direction of coupling vary respectively, which is based on the results of the calculation performed by solving Maxwell's equations using the supercell plane-waves expansion method. The results show that, split photon states change according to the distance between localized photons. When the defect separation becomes large, the interaction between localized modes becomes small, and the parity of the defect mode alternates as the inter-defect distance varies. The defect modes form a defect band in a photonic band gap when the number of coupled point defects increases. The parallel propagating plane waves can excite both the even and odd defect modes. However, the perpendicularly propagating plane waves can excite only the even mode. The defect modes of point defects can be decoupled along diagonal directions where the defect mode decays rapidly, each single micro-cavity is not coupled to its neighbor, and the eigenfrequency is independent of the wavevector.