Strong Coupling of Multimolecular Species to Soft Microcavities

Can we couple multiple molecular species to soft-cavities? The answer to this question has relevance in designing open cavities for polaritonic chemistry applications. Due to the differences in adhesiveness it is difficult to couple multiple molecular species to open cavities in a controlled and precise manner. In this letter, we discuss the procedure to coat multiple dyes, TDBC and S2275, using a layer-by-layer deposition technique onto a dielectric microsphere so as to facilitate the multi molecule coupling. We observed the formation of a middle polariton branch due to the inter-molecular mixing facilitated by the whispering gallery modes. The coupling strength,2g, of the TDBC molecules were found to be 98 meV while that of S2275 molecules was 78 meV. The coupling strength was found to be greater than the cavity linewidth and the molecular absorption linewidth showing the system is in the strong coupling regime.