Directing Monolayer Tungsten Disulfide Photoluminescence using a Bent Plasmonic Nanowire on a Mirror Cavity

TL;DR

This paper demonstrates how a bent plasmonic nanowire on a mirror cavity can direct photoluminescence from monolayer tungsten disulfide, achieving enhanced field and emission directionality for potential on-chip optical applications.

Contribution

The study introduces a novel cavity design using a bent nanowire on a mirror to control and enhance photoluminescence directionality in monolayer TMDs, supported by experimental and numerical analysis.

Findings

Directional emission with narrow wavevector spread

Field enhancement and directivity achieved

Numerical simulations confirm experimental results

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 and a gold mirror. We image the photoluminescence emission wavevectors by using the Fourier plane imaging technique. The cavity out-couples the emission in a narrow range of wavevectors with a radial and azimuthal spreading of only 11.0{\deg} and 25.1{\deg}, 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.