Strong Coupling
Strong coupling may occur between light and matter when reversible exchange of photons takes place between a material and an optical cavity at a rate far greater that any competing dissipative process. This strong interaction leads to the formation of hybrid light–matter states, or polariton states, which are spatially delocalised over macroscopic distances and involve a collective in-phase response of a very large number (~105) of molecules.
Due to polariton states, materials can exhibit enhanced electrical conductivity, variable work functions, increased chemical reactivity, and greatly modified ultrafast energy relaxation pathways.
We study these unusual effects, mainly using metal nanostructures to facilitate the light-matter interaction.
we show that strong light–matter coupling between confined photons on a semiconductor waveguide and localized plasmon resonances on metal nanowires modifies the efficiency of the photoinduced charge-transfer rate of plasmonic derived (hot) electrons into accepting states in the semiconductor material
We have shown a clear correlation between the excitation of waveguide-plasmon polaritons in Al nanowire gratings supported on thin TiO2 films and the decomposition of methyl orange under visible light illumination. We have postulated that this is a consequence of hot-electron injection from Al nanowires into TiO2, a process that is enhanced due to the increased absorption of visible light and decreased radiative damping exhibited by the waveguide-plasmon polaritons.
We present a classical description of the interaction between localized surface plasmon resonances and excitons which can occur in molecular or solid state systems. Our approach consists of adopting a semianalytical description of the surface plasmon resonances in metal nanoparticles and a semiclassical description of the electronic transitions related to the excitonic material.
Our results show that the excited state dynamics of strongly-coupled plasmons and excitons in quantum dots are controlled by the composition of the lower hybrid polariton state.
We present an experimental demonstration of strong coupling between a surface plasmon propagating on a planar silver thin film and the lowest excited state of CdSe nanocrystals. Attenuated total reflection measurements demonstrate the formation of plasmon−exciton mixed states, characterized by a Rabi splitting of ∼112 meV at room temperature. Such a coherent interaction has the potential for the development of nonlinear plasmonic devices, and furthermore, this system is akin to those studied in cavity quantum electrodynamics, thus offering the possibility to study the regime of strong light−matter coupling in semiconductor nanocrystals under easily accessible experimental conditions.
We have shown strong modification of the emis- sion spectrum and decay rate of an organometallic complex when positioned in a metamaterial nanocavity. The approach presented here paves the way for creating efficient optoelectronic devices with transition metal complexes. For instance, one can envisage a light-emitting device where the metal nanostructure and mirror act as the electrodes for charge injection into the active area located in the gap. Simi- larly, the structures presented here may also be engineered for applications in photocatalysis.
