Bistable topological insulator with exciton-polaritons

Functionality of many nonlinear and quantum optical devices relies on the effect of optical bistability. Using the microcavity exciton-polaritons in a honeycomb arrangement of microcavity pillars, we report the resonance response and bistability of the topological edge states. A balance between the pump, loss and nonlinearity ensures a broad range of dynamical stability and controls the distribution of power between counter-propagating states on the opposite edges of the honeycomb lattice stripe. Tuning energy and polarization of the pump photons, while keeping their momentum constant, we demonstrate control of the propagation direction of the dominant edge state. Our results facilitate development of new applications of topological photonics in practical devices.