Core-Bishell Plasmonic Cavities for Tunable Plasmon-Exciton Coupling with Tungsten Disulfide Monolayer

We present a theoretical investigation of plasmon-exciton coupling (PEC) in hybrid nanostructures composed of Ag or Au cores, silicon shells, and an outer monolayer tungsten disulfide (WS2) shell.Using Maxwell-Garnett effective-medium homogenization combined with multilayer Mie theory, we examine the impacts of the core radius and shell thickness on resonance tuning, cavity dissipation, and hybrid-mode formation near the WS2 A-exciton at 619 nm.The study compares three classes of systems: all-dielectric Si-WS2 cavities, metal-WS2 structures, and metal-Si-WS2 core-bishell architectures.This comparative framework is designed to distinguish strong PEC from mere spectral