Multi-mode strong coupling in self-hybridized metasurfacemicrocavity structures

Abstract The stable intrinsic excitons and high refractive index of self-hybridized transition metal dichalcogenides and perovskite metasurfaces enable a significant spatial overlap between excitons and optical resonance modes within the same structure. This capability greatly enhances light confinement, making these systems effective platforms for achieving strong light-matter coupling.Here, we demonstrate multi-mode strong coupling among excitons, guided mode resonance (GMR) and Fabry-Pérot (FP) cavity modes, supported by a three-layer heterostructure photonic crystal (PhC) slab composed of perovskite sandwiched between WS 2 layers and embedded inside an FP optical microcavity. By tuning the exciton oscillator strength, the excited multi-order GMRs can strongly interact with the excitons of WS 2 and perovskite within the PhC slab, reaching the double ultrastrong coupling regime with large Rabi splittings of 431.6 and 595.2 meV, respectively. Moreover, the Rabi splitting of the system can be further enhanced by introducing the FP cavity to realize a triple-mode FP-GMR-exciton coupling, resulting in a giant Rabi splitting energy of 669.2 meV. Crucially, our results reveal that the exciton oscillator strength plays a decisive role in determining the coupling properties of the hybrid system, offering an effective approach to manipulating coupled states. The designed hybrid system proposed in this work can be effectively harnessed to achieve ultrastrong coupling based on self-hybridized architectures and provides a robust platform for exploring ultrahigh Rabi splittings.