Chern Gia-Wei, Saxena Avadh
Opt Lett. 2015 Dec 15;40(24):5806-9. doi: 10.1364/OL.40.005806.
The kagome lattice is a two-dimensional network of corner-sharing triangles and is often associated with geometrical frustration. In particular, the frustrated coupling between waveguide modes in a kagome array leads to a dispersionless flat band consisting of spatially localized modes. Here we propose a complex photonic lattice by placing PT-symmetric dimers at the kagome lattice points. Each dimer corresponds to a pair of strongly coupled waveguides. With balanced arrangement of gain and loss on individual dimers, the system exhibits a PT-symmetric phase for finite gain/loss parameter up to a critical value. The beam evolution in this complex kagome waveguide array exhibits a novel oscillatory rotation of optical power along the propagation distance. Long-lived local chiral structures originating from the nearly flat bands of the kagome structure are observed when the lattice is subject to a narrow beam excitation.
Kagome晶格是一种由角共享三角形构成的二维网络，通常与几何阻挫相关。特别地，Kagome阵列中波导模式之间的阻挫耦合会导致由空间局域模式组成的无色散平带。在此，我们通过在Kagome晶格点处放置PT对称二聚体来提出一种复光子晶格。每个二聚体对应一对强耦合波导。通过在各个二聚体上平衡增益和损耗的配置，该系统在有限增益/损耗参数达到临界值之前呈现PT对称相。这种复Kagome波导阵列中的光束演化表现出光功率沿传播距离的一种新颖的振荡旋转。当晶格受到窄光束激发时，会观察到源自Kagome结构近平带的长寿命局域手性结构。
