Directing monolayer tungsten disulfide photoluminescence using a bent-plasmonic nanowire on a mirror cavity

Abstract

Designing directional optical antennas without compromising the field enhancement requires specially designed optical cavities. Herein, we report on the experimental observations of directional photoluminescence emission from a monolayer tungsten disulfide using a bent-plasmonic nanowire on a mirror cavity. The geometry provides field enhancement and directivity to photoluminescence by sandwiching the monolayer between an extended cavity formed by dropcasting bent-silver nanowire on a gold mirror. We image the photoluminescence emission wavevectors using Fourier plane imaging technique. The cavity outcouples the emission in a narrow range of wavevectors with a radial and azimuthal spreading of only 11.0∘ and 25.1∘, respectively. Furthermore, we performed three-dimensional finite difference time domain-based numerical calculations to corroborate and understand the experimental results. We envisage that the results presented here will be readily harnessed for on-chip coupling applications and in designing inelastic optical antennas.