Angle-independent strong coupling between plasmonic magnetic resonances and excitons in monolayer WS2.

The room-temperature strong coupling between plasmonic magnetic resonances (MRs) of metal gratings and excitons in monolayer WS2 is intensively investigated. Both numerical simulations and theoretical calculations indicate that the strong coupling between MRs and excitons enables the remarkable spectral splitting. The typical anticrossing behavior with the Rabi splitting up to 86.5 meV is realized on the color-coded absorption spectra by changing the nanogroove depth, width, and the refractive index of the dielectric filled into nanogrooves, respectively. Interestingly, such strong coupling can also be achieved by using WS2 ribbons instead of the monolayer and simultaneously is dynamically controlled by varying the interaction area. More importantly, the observed MR-exciton coupling is angle-independent. Our findings thus suggest a possible way toward enhancing light-matter interactions in monolayer transition-metal dichalcogenides and play significant roles in quantum and nonlinear nanophotonic devices at ambient conditions.