Bulk transition metal dichalcogenide disk-ring nanoresonators for intrinsic strong light-matter interaction

Multilayer and bulk transition metal dichalcogenides (TMDs) have become alternative platforms for strong light-matter coupling due to their high refractive index and the ability to excite optical modes. In particular, strong coupling between intrinsic excitons and the anapole mode (AM) excited by bulk TMDs has received widespread attention due to the suppressed far-field radiation and enhanced near-field confinement caused by AM. Here, we propose an all-dielectric self-hybridizing disk-ring resonator made of bulk TMD material. We demonstrate that an abnormal anapole mode (AAM) can be excited by the interaction of the AM excited by a single disk with the magnetic quadrupole $({Q}_{m})$ mode excited by a single ring. Importantly, we conduct a detailed analysis of the coherent and incoherent strong-coupling processes involving AAM, AM, and intrinsic excitons. Our findings indicate that the AM-exciton strong coupling exhibits reduced incoherent coupling, which we qualitatively attribute to the suppression of radiation decay in AM compared to AAM, thereby inhibiting energy exchange between the system and the continuum base. Furthermore, we demonstrate the robustness of the strong coupling in this system concerning structural parameters, and we explain that this robustness arises from the relatively small contribution of the $({Q}_{m})$ mode excited by the ring in the coupling process. Such a self-hybridizing nanostructure provided by this theoretical work may not only offer an attractive platform to explore light-matter interaction in the strong-coupling regime, but it may also show potential applications in realizing novel nanophotonic optical devices.