Dispersion Control of Chiral Exciton-Polariton Transport with Dielectric Metasurfaces

Abstract

Exciton-polaritons provide a powerful platform for manipulating hybrid light-matter states with low effective masses and strong nonlinearities. Introducing chirality into these quasiparticles enables selective control over their spin and propagation, opening new opportunities for chiral transport and spin-selective polaritonic devices. We exploit the strong chiral light-matter coupling in silicon metasurfaces composed of tilted nanorod dimers to demonstrate selective transport of organic chiral exciton-polaritons. The metasurface supports surface lattice resonances and quasi-bound states in the continuum that simultaneously provide high photonic confinement and extrinsic chirality, giving rise to chiral exciton-polaritons in the achiral molecules. These exciton-polaritons exhibit a large magnitude of the dissymmetry factor, reaching a value of 0.93. Using photoluminescence Fourier microscopy and real-space imaging, we show that chiral exciton-polaritons propagate over distances exceeding 50 um without significant degradation of their dissymmetry, with characteristic propagation lengths of approximately 6-13 um. These propagation lengths correspond to an enhancement of 3 orders of magnitude compared to bare excitons. This work constitutes the first demonstration of enhanced and selective chiral transport of organic exciton-polaritons, driven by strong light-matter coupling, in achiral metasurfaces, paving the way for spin-selective polaritonic technologies using simple metasurfaces.