This study is conducted in collaboration with Antoine Moreau, Department of Electromagnetism and Nanophotonics, Blaise Pascal Institute, France.

For the numerical modeling of light/metal interactions at the nanoscale, the choice of an appropriate material model is a crucial point. Approaches that are adopted in a first instance are based on local (i.e. with no interaction between electrons) dispersive models (e.g. Drude or Drude-Lorentz models). From the mathematical point of view, when a time-domain modeling is considered, these models lead to an additional system of ordinary differential equation which is coupled to Maxwell's equations. When it comes to very small structures in a regime of 2 nm to 10 nm, non-local effects due to electron collisions have to be taken into account. Physically, such effects leads to additional system of partial differential equations coupled to the Maxwell system.

Here, we illustrate the resonance of a 2nm-radius gold nanosphere described by a local (top) and linarized, non-local (bottom) Drude model. The wavelets that can be seen inside the metal in the non-local case are known as bulk plasmons.

A DGTD method for the numerical modeling of the interaction of light with nanometer scale metallic structures taking into account non-local dispersion effects

Nikolai Schmitt, Claire Scheid, Stephane Lanteri, Antoine Moreau, Jonathan Viquerat

Journal of Computational Physics, Vol. 316, pp. 396-415 (2016)