Manipulation of waves in Polariton Topological Insulators.

As a frontier in condensed matter physics, the concept of topological insulators has been successfully extended from electronic systems to photonic systems and even to structured microcavities, where strong photon-exciton coupling gives rise to hybrid part-light, part-matter exciton-polaritons quasiparticles. Polaritons inherit the low-loss, tunable characteristics of photons while retaining strong excitonic nonlinear interactions, offering an ideal nonequilibrium platform for exploring topological states. This review systematically surveys the progress of topological insulators in exciton-polariton systems, with emphasis on their underlying physical mechanisms, exotic quantum phenomena induced by various strategies, and the impact of nonlinear effects on topological states. Finally, we discuss the key challenges currently facing this field and provide an outlook on future research directions.