论文标题
通过模式干扰设计的一系列光学波导中的拓扑状态
Topological states in arrays of optical waveguides engineered via mode interference
论文作者
论文摘要
具有拓扑非平凡带的光子结构通常是通过在精心设计的光子晶格中与对称性的精心设计的简单元原子（理想情况下是单模的单模）设计的，可确保拓扑状态的出现。在这里，我们研究了不需要复杂的晶格几何形状的替代选项，而是依赖于单个元原子的参数的调整来实现具有不同对称性模式的脱落性。作为一个说明性的例子，我们考虑了一个等距的一维阵列，具有强烈不对称的近场剖面，从而支持退化模式，从而导致耦合调制。利用此功能，我们证明了所提出的系统支持拓扑边缘模式，并且可以看作是范式Su-Schrieffer-Heeger模型的概括，并减少了它以选择合适的参数选择。因此，我们的结果通过模式干扰为工程拓扑状态提供了一条途径，该途径进一步扩展了光子学中可用的拓扑结构的大量拓扑结构，这对于非线性拓扑系统尤其有希望。
Photonic structures with topologically nontrivial bands are usually designed by arranging simple meta-atoms, ideally, single-mode ones, in a carefully designed photonic lattice with symmetry that guarantees the emergence of topological states. Here we investigate an alternative option that does not require complex lattice geometry but instead relies on the tuning of the parameters of the individual meta-atoms to achieve the degeneracy of the modes with different symmetry. As an illustrative example, we consider a one-dimensional array of equidistant identical periodic nanophotonic waveguides supporting degenerate modes with strongly asymmetric near field profiles giving rise to the coupling modulation. Exploiting this feature, we demonstrate that the proposed system supports topological edge modes and can be viewed as a generalization of the paradigmatic Su-Schrieffer-Heeger model, reducing to it for the suitable parameter choice. Our results thus provide an avenue to engineer topological states via mode interference which further expands the plethora of topological structures available in photonics being especially promising for nonlinear topological systems.
