Mirror-Coupled Microsphere can narrow the Angular distribution of Photoluminescence from WS2 Monolayers

Engineering optical emission from two dimensional, transition metal dichalcogenides (TMDs) materials such as Tungsten disulphide (WS2) has implications in creating and understanding nanophotonic sources. One of the challenges in controlling the optical emission from 2D materials is to achieve narrow angular spread using a simple photonic geometry. In this paper, we study how the photoluminescence of a monolayer WS2 can be controlled when coupled to film coupled microsphere dielectric antenna. Specifically, by employing Fourier plane microscopy and spectroscopic techniques, we quantify the wavevector distribution in the momentum space. As a result, we show beaming of the WS2 photoluminescence with angular divergence of {\theta}1/2 = 4.6{\deg}. Furthermore, the experimental measurements have been supported by three-dimensional numerical simulations. We envisage that the discussed results can be generalized to a variety of nanophotonic 2D materials, and can be harnessed in nonlinear and quantum technology.