# Electrically tunable strong coupling in a hybrid-2D excitonic metasurface for optical modulation

## TL;DR

Researchers developed a metasurface that can electrically control light using 2D materials, achieving high modulation efficiency at room temperature.

## Contribution

A hybrid-2D excitonic metasurface is introduced that enables strong and electrically tunable exciton-photon coupling at ambient conditions.

## Key findings

- A free-space optical modulator with 9.9 dB reflectance modulation is experimentally demonstrated.
- The electro-optic response is mediated by changes in free carrier concentration, affecting exciton decay rates.

## Abstract

Atomically thin semiconductors exhibit tunable exciton resonances that can be harnessed for dynamic manipulation of visible light in ultra-compact metadevices. However, the rapid nonradiative decay and dephasing of excitons at room temperature limit current active excitonic metasurfaces to a few-percent efficiencies. Here, we leverage the combined merits of pristine 2D heterostructures and non-local dielectric metasurfaces to enhance the excitonic light-matter interaction, achieving strong and electrically tunable exciton-photon coupling at ambient conditions in a hybrid-2D excitonic metasurface. Using this, we realize a free-space optical modulator and experimentally demonstrate 9.9 dB of reflectance modulation. The electro-optic response, characterized by a continuous transition from strong to weak coupling, is mediated by gating-induced variations in the free carrier concentration, altering the exciton’s nonradiative decay rate. These results highlight how hybrid-2D excitonic metasurfaces offer novel opportunities to realize nanophotonic devices for active wavefront manipulation and optical communication.

Electrically tunable strong coupling is achieved at ambient conditions in an excitonic metasurface, enabling 9.9 dB of free-space optical modulation.