Manipulating strong coupling between exciton and quasibound states in the continuum resonance

Strong coupling exhibits the 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 line shapes of the coupled systems. Here we set an example to manipulate the strong coupling in a hybrid structure composed of excitons in monolayer ${\mathrm{WS}}_{2}$ and quasibound states in the continuum supported by the ${\mathrm{TiO}}_{2}$ 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 strong light--matter coupling to meet diversified application requests.