Intrinsic strong light-matter coupling with self-hybridized bound states in the continuum in van der Waals metasurfaces

Photonic bound states in the continuum (BICs) provide a standout platform for strong light-matter coupling with transition metal dichalcogenides (TMDCs) but have so far mostly been implemented as traditional all-dielectric metasurfaces with adjacent TMDC layers, incurring limitations related to strain, mode overlap and material integration. Here, we demonstrate intrinsic strong coupling in BIC-driven metasurfaces composed of nanostructured bulk tungsten disulfide (WS2) and exhibiting resonances with sharp, tailored linewidths and selective enhancement of light-matter interactions. Tuning of the BIC resonances across the exciton resonance in bulk WS2 is achieved by varying the metasurface unit cells, enabling strong coupling with an anticrossing pattern and a Rabi splitting of 116 meV. Crucially, the coupling strength itself can be controlled and is shown to be independent of material-intrinsic losses. Our self-hybridized metasurface platform can readily incorporate other TMDCs or excitonic materials to deliver fundamental insights and practical device concepts for polaritonic applications. The authors demonstrate strong coupling in bound state in the continuum metasurfaces on nanostructured bulk WS2 and exhibiting sharp resonances with tailored linewidths and controllable light-matter coupling strength.

Automated summary

In this study, strong coupling in bound state in the continuum metasurfaces on nanostructured bulk WS2 is demonstrated, with sharp resonances, tailored linewidths, and controllable light-matter coupling strength.