Molecule-Plasmon MetaHybrids – PlasHybrid

In plasmonic strong coupling, molecules can be coherently coupled through the plasmon on a scale up to tens of microns, drastically affecting the otherwise independent emitters. PlasHybrid aims to exploit such extended interaction to generate original physical processes and materials with new functionalities. Strong coupling between excitons and surface plasmons occurs when the plasmon/emitters interaction overcomes the damping in the system. In this particular regime of light-matter interaction, the surface plasmon mode hybridizes with the molecular excited states (Frenkel excitons for J-aggregated dyes or excitation in molecules) to form polariton states. Due to its spatial extension, a delocalized plasmon strongly coupled to a set of localized emitters (molecules) generates a spatial coherence which can extend on several microns. We will exploit the extended interaction in three different ways: by periodically structuring an optically active material within the coherence length to create metasurfaces, by studying an individual emitter or patch of emitters coupled to a remote set of molecules, and finally by coupling two different organic materials through a plasmon. The main objectives that derive from these research directions are the following:

•Strong coupling based plasmonic metamaterials, polarization anisotropy
The spatial extension of the hybridized states allows a new type of material organization. Until now the merging of different materials in strong coupling has always been achieved by stacking layers of different molecules. As the coherent state with surface plasmon extends laterally on several microns, it is possible to structure the material in the plane of the films. This new degree of freedom for the coupling is made possible by the simplicity of the plasmonic devices, which allow an easy access and structuration of the molecular systems deposited directly on the planar metal film. The polaritonic metasurfaces generated by this method will be studied and applied to the generation of emission anisotropy and original plasmonic band structures.

•Exploitation of the extended coherence length to perform all optical, non-local, switching and statistics on single-photon emitters
When an emitter (or a collection of emitters) is added or activated within the coherence length of a system in strong coupling, the transition energies are modified as they are related to the total number of emitters in interaction. As the coherence length is large, this modification offers an original way to perform switching (and modulation) with a remote control. In addition, the photon statistics associated with a single emitter progressively included in a strongly coupled system should be drastically modified. This emission statistic has been widely studied in weak coupling regime, but never in the strong coupling regime.

•Demonstration of energy transfer over distances up to ten microns
The strong coupling offers a very efficient way to couple different molecular materials in the sense that the states of the different molecular systems hybridized with the same plasmon cannot be separated anymore. Based on this transfer mechanism and on the large spatial extension of hybrid states, three orders of magnitude can be gained in energy transfer distances.

The demonstration of enhanced energy transport over long distances as well as non-local control of properties and the hybridization of different materials will increase our fundamental understanding of strong coupling and open totally new possibilities in other areas such as organic photovoltaics or organic electronics.