WS₂ monolayers coupled to hyperbolic metamaterial nanoantennas: Broad implications for light-matter-interaction applications

Because of their atomic-layer thickness, direct band gap, mechanical robustness, and other superior properties, transition metal dichalcogenide (TMDC) monolayers are considered as an attractive alternative to graphene for diverse optoelectronic applications. However, because of the very nature of their atomic-layer thickness, the interaction of light with TMDCs is limited, hindering the overall efficiency for optical applications. Therefore, for TMDCs to become a true candidate as the material of choice for optoelectronics, there is a need for a mechanism that significantly enhances the interaction of light with TMDCs. In this paper, we demonstrate about 30-fold enhancement of the overall photoluminescence emission intensity from a WS₂ monolayer, by its coupling to a hyperbolic metamaterial nanoantenna array. This enhancement corresponds to nearly 300-fold enhancement per individual nanoantenna. This overall enhancement is achieved by the combination of enhancing the excitation (absorption) efficiency and enhancing the radiative decay rate. Our result paves the way for the use of TMDCs in diverse optoelectronic applications, ranging from light sources and photodetectors to saturated absorbers and nonlinear media.