Enhanced and directional light emission from two-dimensional excitons using Mie voids

TL;DR

This paper demonstrates how Mie voids in van der Waals semiconductors can significantly enhance and direct light emission from 2D excitons, enabling efficient nanoscale light sources with tunable properties.

Contribution

It introduces a novel all-van der Waals platform coupling excitons to Mie void resonators, with a fabrication method allowing independent control of void geometry for optimized emission.

Findings

Up to 600-fold increase in photoluminescence intensity.

Pronounced out-of-plane light beaming with 2.6 dB forward-to-off-axis enhancement.

Systematic tuning of optical response through void geometry control.

Abstract

Controlling light emission at the nanoscale has important applications in solid-state lighting, displays, and quantum light sources. Achieving this control requires both enhanced local electromagnetic fields to boost emission intensity and engineered radiation patterns to direct photons efficiently. Mie voids, consisting of an air cavity surrounded by a high-index semiconductor, are particularly suited for this purpose because they expose their strongest fields in an accessible region for nearby emitters while supporting resonances that shape directional emission through interference. Here, we demonstrate an all-van der Waals nanophotonic platform that couples excitons in atomically thin WS$_2$ to Mie void resonators formed in WSe$_2$. Guided by electromagnetic simulations, we identify void geometries that maximize photoluminescence through synergistic enhancement of excitation and emission processes. We also develop a two-step fabrication strategy that enables independent control of void diameter and depth, providing a route to systematically tune the optical response. Experimentally, we observe up to a 600-fold increase in photoluminescence intensity from monolayer WS$_2$ placed on individual voids compared to on an unstructured WSe$_2$, along with pronounced out-of-plane beaming of light that yields a forward-to-off-axis enhancement of 2.6 dB. Our results establish Mie voids in van der Waals semiconductors as a new platform for controlling light-matter interactions and realizing compact, directional, and efficient nanoscale light sources.