Tunable Fabry–Perot Microcavity Based on Boron Nitride and Rhodamine 6G.

Light–matter interaction leads to excitation of molecules, which, in turn, can exchange energy with a localized electromagnetic field. This can be used for engineering of the electronic and vibrational energy levels of the molecules. This study considers the conditions for the emergence of the strong light–matter coupling regime for organic dye molecules in a tunable Fabry–Perot microcavity formed by a convex mirror and a flat reflecting surface. The sample studied was made of hexagonal boron nitride (hBN), polyvinylpyrrolidone polymer (PVP, 55 kDa), and rhodamine 6G fluorophore (R6G). Strong light–matter coupling was obtained in a sample with a low concentration of PVP. Adjustment of the optical path length in the microcavity by varying the thickness of the hBN–R6G–PVP film made it possible to obtain a high density of modes in the cavity (several tens of (λ/n)3) and, hence, to study the weak and strong light–matter coupling regimes. The results offer the possibility of studying the basic mechanisms of resonant light–matter interaction at room temperature, as well as developing new practical applications of the strong coupling effect. [ABSTRACT FROM AUTHOR]