Manipulating strong coupling between exciton and quasi-bound states in the continuum resonance

TL;DR

This paper develops an analytical framework to understand and control strong exciton-coupled states in hybrid nanostructures, demonstrating tunable spectral splitting in a WS$_2$-TiO$_2$ metasurface system.

Contribution

It introduces a combined tight-binding and coupled-mode theory approach to analyze and tailor strong light-matter interactions in hybrid nanostructures.

Findings

Spectral splitting can be controlled by adjusting the nanodisk metasurface asymmetry.

The theoretical model accurately predicts the absorption spectra.

The approach enhances understanding of physical parameters influencing strong coupling.

Abstract

Strong coupling exhibits unique ability to preserve quantum sates between light and matter, which is essential for the development of quantum information technology. To explore the physical mechanism behind this phenomenon, we employ the tight-binding method for expanding the temporal coupled-mode theory, with the absorption spectrum formula of coupled system directly obtained in an analytical way. It reveals all the physical meaning of parameters defined in our theory, and shows how to tailor lineshapes of the coupled systems. Here, we set an example to manipulate the strong coupling in a hybrid structure composed of excitons in monolayer WS$_2$ and quasi-bound states in the continuum supported by the TiO$_2$ nanodisk metasurfaces. The simulated results show that a clear spectral splitting appeared in the absorption curve, which can be controlled by adjusting the asymmetric parameter of the nanodisk metasurfaces and well fitted through our theoretical predictions. Our work not only gives a more comprehensive understanding of such coupled systems, but also offers a promising strategy in controlling the strong light-matter coupling to meet diversified application requests.