Coherent and incoherent damping pathways mediated by strong coupling of two-dimensional atomic crystals with metallic nanogrooves

Abstract

In this paper we investigate the strong exciton-plasmon coupling in a hybrid system consisting of an atomic thick ${\mathrm{WS}}_{2}$ monolayer and a gold nanogroove array. We theoretically identify the coexistence of two damping pathways: a coherent damping pathway resulting from the resonant dipole-dipole interaction and a coupling-induced incoherent damping pathway due to the spontaneous emissions of a photon by one subsystem and its subsequent reabsorption by the other. We show that the interplay between both interaction processes not only determines the optical property of the hybrid system, but also results in a pronounced modification of the radiative damping due to the formation of super- and subradiant polariton states. Importantly, we reveal that the radiative damping property of the polariton modes is determined only by the effect of coupling-induced sub- and super-radiance, which is distinctly different from that previously observed in a metal-molecular hybrid system where pure dephasing of J-aggregate excitons dominates the polariton dynamics. Our findings may pave the way towards active manipulation of polariton dynamics and offer possibilities for realizing coherent active control in novel plasmonic devices.