Zhang Yiqi, Kartashov Y V, Torner L, Li Yongdong, Ferrando A
Opt Lett. 2020 Sep 1;45(17):4710-4713. doi: 10.1364/OL.396039.
We address the resonant response and bistability of the exciton-polariton corner states in a higher-order nonlinear topological insulator realized with a kagome arrangement of microcavity pillars. Such states are resonantly excited and exist due to the balance between pump and losses, on one hand, and between nonlinearity and dispersion in inhomogeneous potential landscape, on the other hand, for pump energy around eigen-energies of corresponding linear localized modes. Localization of the nonlinear corner states in a higher-order topological insulator can be efficiently controlled by tuning pump energy. We link the mechanism of corner state formation with symmetry of the truncated kagome array. Corner states coexist with densely packed edge states but are well isolated from them in energy. Nonlinear corner states persist even in the presence of perturbations in a corner microcavity pillar.
我们研究了由微腔柱的 kagome 排列实现的高阶非线性拓扑绝缘体中激子 - 极化激元角态的共振响应和双稳性。一方面，由于泵浦与损耗之间的平衡，另一方面，由于非均匀势场中非线性与色散之间的平衡，对于泵浦能量在相应线性局域模的本征能量附近时，此类角态会被共振激发并存在。通过调节泵浦能量，可以有效地控制高阶拓扑绝缘体中非线性角态的局域化。我们将角态形成的机制与截断的 kagome 阵列的对称性联系起来。角态与密集堆积的边缘态共存，但在能量上与它们很好地隔离。即使在角微腔柱存在微扰的情况下，非线性角态仍然存在。
