Topological phases and edge states in a non-Hermitian trimerized optical lattice
Topological phases and edge states in a non-Hermitian trimerized optical lattice
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非厄米三聚光学晶格中的拓扑相和边缘态
DOI：
10.1103/physreva.96.032103
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发表时间：
2017-09-05
影响因子：
2.9
通讯作者：
Jin, L.
中科院分区：
文献类型：
--
作者：
Jin, L.
拓扑学设计的光学材料支持强大的光传输。在这里，所研究的非厄米特晶格是三聚化的，并使用均匀的胞内耦合进行非均匀耦合。计算了耦合波导晶格的拓扑性质，发现对称晶格的对称相可以有不同的拓扑结构，边缘状态取决于晶格的大小、边界构型以及耦合与非赫米性之间的竞争。在存在周期增益和周期损耗的情况下，拓扑域的非平凡区域被扩展。Bloch带积累的非零几何位相表明在带隙之间存在拓扑保护的边缘态。单向放大和衰减零模出现在非赫米性阈值以上，这有利于发展一种健壮的光学二极管。
Topologically engineered optical materials support robust light transport. Herein, the investigated non-Hermitian lattice is trimerized and inhomogeneously coupled using uniform intracell coupling. The topological properties of the coupled waveguide lattice are evaluated and we find that the $\mathcal{PT}$-symmetric phase of a $\mathcal{PT}$-symmetric lattice can have different topologies; the edge states depend on the lattice size, boundary configuration, and competition between the coupling and degree of non-Hermiticity. The topologically nontrivial region is extended in the presence of periodic gain and loss. The nonzero geometric phases accumulated by the Bloch bands indicate the existence of topologically protected edge states between the band gaps. The unidirectional amplification and attenuation zero modes appear above a threshold degree of non-Hermiticity, which facilitates the development of a robust optical diode.