Strong interaction of quantum emitters with a WS layer enhanced by a gold substrate.

We investigate the spontaneous emission (SE) effects of a two-level quantum emitter (QE) near a WS layer. The QE is placed above the WS layer in a host medium with constant dielectric permittivity. The material below the WS layer is either the same as the host medium or Au. We find that the Purcell factor of the QE near the dielectric/WS takes values up to 10. When the value of the dielectric permittivity of the host medium is increased, the enhancement of the Purcell factor diminishes. For a dielectric/WS/dielectric structure, we obtain a Rabi splitting in the SE spectrum of the QE up to 75 meV at room temperature. This splitting is more pronounced for a WS layer of improved material quality which can be achieved by improved fabrication methods or operating at lower temperatures. When the WS layer is placed on top of an Au substrate, the hybrid exciton-surface plasmon polariton modes strongly interact with the QE, inducing coherent energy exchange between the two, as manifested by a pronounced Rabi splitting in the emission spectrum which is increased to 100 meV.