Manipulation of intrinsic light-matter interaction in a single self-hybridizing WS 2 nanodisk

Bulk transition metal dichalcogenides (TMDs) materials exhibit surprisingly high refractive index in visible to infrared range. Bulk TMD-based nanostructures can therefore serve as excellent resonant nanoresonators supporting various types of optical modes, which can in turn hybridize with TMD excitons in the same material. Such self-hybridizing structures are becoming attractive candidates for the study of intrinsic light-matter interactions due to its excellent mode overlap. However, very few studies have been reported on flexible tuning of intrinsic coupling in bulk TMD-based nanoresonators. Here, we propose a simple self-hybridizing nanoparticle-on-mirror (NPoM) system consisting of a single tungsten disulfide (${\mathrm{WS}}₂$) nanodisk placed on a metallic reflector deposited with a thin dielectric layer. We demonstrate a flexible tuning of self-hybridization of intrinsic TMD excitons with magnetic Mie mode and anapole, which is controlled by the size of the ${\mathrm{WS}}₂$ disk. Importantly, we show that the coupling strength of the system can be further modulated by tuning the thickness of the dielectric layer, enabling us to bring the system from weak to intermediate, and even to a strong coupling regime. Theoretical modeling combined with near-field analysis reveals that such an effective modulation on the coupling strength results from the variation of field confinement and number of excitons involved in the intrinsic coupling process. The proposed self-hybridizing system provides a promising platform for the study of highly tunable intrinsic light-matter interactions and may pave the way for the development of high-performance TMD-based tunable polaritonic devices.