Strong coupling between excitons and magnetic dipole quasi-bound states in the continuum in WS$_2$-TiO$_2$ hybrid metasurfaces

TL;DR

This paper theoretically demonstrates strong exciton-photonic mode coupling in WS$_2$-TiO$_2$ hybrid metasurfaces, showing spectral splitting and anticrossing behavior, with tunability via structural parameters, advancing quantum photonic device design.

Contribution

It introduces a novel hybrid metasurface design enabling controllable strong coupling between excitons and quasi-BIC modes in monolayer WS$_2$.

Findings

Spectral splitting and anticrossing observed in the hybrid structure.

Strong coupling modulated by metasurface thickness and asymmetry.

Balance of mode linewidth and electric field enhances coupling efficiency.

Abstract

Enhancing the light-matter interactions in two-dimensional materials via optical metasurfaces has attracted much attention due to its potential to enable breakthrough in advanced compact photonic and quantum information devices. Here, we theoretically investigate a strong coupling between excitons in monolayer WS$_2$ and quasi-bound states in the continuum (quasi-BIC). In the hybrid structure composed of WS$_2$ coupled with asymmetric titanium dioxide nanobars, a remarkable spectral splitting and typical anticrossing behavior of the Rabi splitting can be observed, and such strong coupling effect can be modulated by shaping the thickness and asymmetry parameter of the proposed metasurfaces. It is found that the balance of line width of the quasi-BIC mode and local electric field enhancement should be considered since both of them affect the strong coupling, which is crucial to the design and optimization of metasurface devices. This work provides a promising way for controlling the light-matter interactions in strong coupling regime and opens the door for the future novel quantum, low-energy, distinctive nanodevices by advanced meta-optical engineering.