Optically induced topological spin-valley Hall effect for exciton polaritons

Abstract

We consider exciton-polaritons in a honeycomb lattice of micropillars subjected to circularly polarized (σ±) incoherent pumps, which are arranged to form two domains in the lattice. We predict that the nonlinear interaction between the polaritons and reservoir excitons gives rise to the topological valley Hall effect, where in each valley two counter propagating helical edge modes appear. Under a resonant pump, σ± polaritons propagate in different directions without being reflected around bends. The polaritons propagating along the interface have extremely high effective lifetime and also show fair robustness against disorder. This paves the way for robust excitonpolariton spin separating and transporting channels, in which polaritons attain and maintain high degree of spin polarization, even in the presence of spin relaxation.