We analyze the optical spectra of photonic structures composed of hBN films with embedded WS2 excitonic monolayers, designed to maximize light–matter interaction and Rabi splittings. These structures are enclosed within SiO2 layers and probed in an attenuated total reflection configuration using Si prisms. The optical spectra show resonances due to strong exciton–guided mode interactions and the prism dispersion. For a straightforward structure made of five identical stacked cells with a total width of L=1050nm, we obtained a Rabi splitting of 238.2meV between the lowest resonances, already exceeding the 151meV splitting recently reported for a relatively complex structure As’ham et al., Phys. Rev. Appl. 19, 054049 (2023). Choosing the positions of the WS2 layers close to the antinodes of the guided modes, we found three resonances with an even larger splitting of 244.8meV between the middle and lower resonances and 95.6meV between the upper and middle ones, covering a range of 340.4meV. Two of the resonances arise from a Rabi-like coupling of a guided mode and an excitonic mode, while the third is due to dispersion in the coupling prisms. Thinner heuristically optimized structures with L=734nm and L=409nm, containing only three and two excitonic monolayers and coupled to guided modes with two and one node, yielded even larger splittings, 248.6+102.0meV=350.6meV and 255.9+126.3meV=382.2meV, respectively. We believe such simple photonic structures supporting three well-defined resonances arising from strong exciton–guided mode coupling under dispersive conditions are promising for polaritonic device design.
Valdés-Negrin et al. (Thu,) studied this question.