Nonlinear higher-order polariton topological insulator

TL;DR

This paper investigates the resonant response and bistability of nonlinear exciton-polariton corner states in a higher-order topological insulator with a kagome lattice, demonstrating controllable localization and robustness of these states.

Contribution

It introduces the realization and control of nonlinear corner states in a higher-order topological insulator using a kagome microcavity array, linking their formation to lattice symmetry.

Findings

Corner states are resonantly excited and bistable.

Localization can be tuned by pump energy.

Corner states are robust against perturbations.

Abstract

We address the resonant response and bistability of the exciton-polariton corner states in a higher-order nonlinear topological insulator realized with kagome arrangement of microcavity pillars. Such states are resonantly excited and exist due to the balance between pump and losses, on the 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 corner microcavity pillar.