Numerical model studies of energy transfer processes in strong coupled exciton-plasmon systems

The optical response of metal-dielectric and molecular nanostructures has been attracting considerable attention in the last few decades due to many potential, as well as already realized applications, such as plasmonic circuitry, plasmonic sensing, wave-guiding, solar cells, biomedical applications, and many others.

In this work we are investigating the optical response of 2D systems made of single and coupled nanoparticles in the presence of molecular assemblies. Our goal is to gain a further understanding of the way strong exciton-plasmon coupling affects scattered field lineshapes, light propagation and heat development within the metal-molecules composites.

The study is carried out using the Finite Difference Time Domain (FDTD) algorithm. We describe the metal nanoparticles through the simple Drude dielectric model, while the molecules are modeled as two-level systems. The field-matter interaction is calculated in a self-consistent manner, by solving the coupled Maxwell-Bloch equation, and using a mean field approximation.

We use a home-build code in which the FDTD grid is decomposed into several slices and the Maxwell equations in each slice are computed by a different processor. This parallel evaluation of the FDTD algorithm allows us to minimize time and computer memory costs, which is highly important in 3D FDTD calculations, but is also very efficient in our 2D simulations.

We display results for various configurations of metal-molecule composites, and show how the excitom-plasmon coupling is manifested in energy transfer processes within such systems. In addition, we explore the conditions for the metal-molecule composites that can give rise to time-resolved oscillations.

In the future, we plan to expand our calculations to more complex and realistic 3D configurations.