Mirror-coupled microsphere can narrow the angular distribution of photoluminescence from WS2 monolayers

Abstract

Engineering optical emission from two-dimensional, transition metal dichalcogenides, such as tungsten disulfide (WS2), has implications in creating and understanding nanophotonic sources. One of the challenges in controlling the optical emission from two-dimensional materials is to achieve narrow angular spread using simple photonic geometry. In this article, we study how the photoluminescence of a monolayer WS2 can be controlled when coupled to a 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 the beaming of the WS2 photoluminescence with angular divergence as low as θ1/2 = 4.6°. 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 two-dimensional materials and can be harnessed for on-chip nonlinear and quantum technology.