Hybrid THz architectures for molecular polaritonics

We explore several schemes of electromagnetic field confinement aimed at facilitating the collective strong coupling of a localized photonic mode to molecular vibrations in the terahertz region. The key aspects are the use of plasmonic metasurface structures combined with standard Fabry-Perot configurations and the deposition of a thin layer of glucose, via a spray coating technique, within a tightly focused electromagnetic mode volume. We observe vacuum Rabi splittings reaching up to 140 GHz and study the complex interplay between plasmonic resonances, photonic cavity modes and low-energy molecular resonances. Our study provides key insight into the design of polaritonic platforms with organic molecules to harvest the unique properties of hybrid light-matter states.