Strong interaction of quantum emitters with a WS₂ layer enhanced by a gold substrate

We investigate the spontaneous emission (SE) effects of a two-level quantum emitter (QE) near a WS₂ layer. The QE is placed above the WS₂ layer in a host medium with constant dielectric permittivity. The material below the WS₂ layer is either the same as the host medium or Au. We find that the Purcell factor of the QE near the dielectric/WS₂ takes values up to 10⁴. When the value of the dielectric permittivity of the host medium is increased, the enhancement of the Purcell factor diminishes. For a dielectric/WS₂/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 WS₂ layer of improved material quality which can be achieved by improved fabrication methods or operating at lower temperatures. When the WS₂ 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.