  Two-dimensional semiconducting transition metal dichalcogenides (TMDCs) are
extremely attractive materials for optoelectronic applications in the visible
and near-IR range. Here, we address for the first time to the best of our
knowledge the issue of resonance coupling in hybrid exciton-polariton
structures based on single Si nanoparticles coupled to monolayer WS2. We
predict a transition from weak to strong coupling regime , with a Rabi
splitting energy exceeding 200 meV for a Si nanoparticle covered by monolayer
WS 2 at the magnetic optical Mie resonance. This large transition is achieved
due to the symmetry of magnetic dipole Mie mode and by changing the surrounding
dielectric material from air to water. The prediction is based on the
experimental estimation of TMDC dipole moment variation obtained from measured
photoluminescence (PL) spectra of WS2 monolayers in different solvents. An
ability of such a system to tune the resonance coupling is realized
experimentally for optically resonant spherical Si nanoparticles placed on a
WS2 monolayer. The Rabi splitting energy obtained for this scenario increases
from 49.6 meV to 86.6 meV after replacing air by water. Our findings pave the
way to develop high-efficiency optoelectronic, nanophotonic and quantum optical
devices.
