Properties of surface plasmons strongly coupled to excitons in an organic semiconductor near a metallic surface

The properties of organic semiconductor excitons in strong interaction with surface plasmons are described. For this purpose, a J-aggregated cyanine dye layer is deposited on a silver film and studied with reflectometry experiments. The dependence of the Rabi splitting with the square root of the dye layer absorption and the width inversion of the reflectometry lines at the resonance are observed. The experimental spectra are well fitted using a transfer matrix method with a complex index. The comparison between experiments and simulations for layers in different configurations is qualitatively related to the role of the plasmon polarization in the interaction with the aggregated dye chains. Finally, large Rabi splitting of 300 meV are observed for pure dye layers. Characteristic behavior of the large coupling and the effect of asymmetrical absorption line shape are analyzed.