Organic Exciton-Polariton Condensation in Metasurfaces

We demonstrate strong light-matter coupling of excitons in organic dyes and photons in a cavity formed by a silicon metasurface. The metasurface consists of an array of nanodisks supporting Mie-surface lattice resonances (SLRs). For sufficiently high pump fluences, exciton-polaritons condense in a bound-state in the continuum, i.e. at an energy in which the Mie-SLR has no losses. This suppression of the losses leads to a low condensation threshold, which can be used for an efficient non-linear emission.