Thesis of Zoheir ZIANI

Thesis defense of Zoheir ZIANI    - laboratory EPHONI Abstract : Nonlinear plasmonics is a largely unexplored field and only a few nonlinear interactions in metal nanostructures have been investigated so far.
This thesis work focuses on the appearance of nonlinear surface plasmon modes in metal nanostructures (dimer, chains of nanoparticles) inserted in a dielectric matrix, and subjected to the action of an external electromagnetic source of the plane wave type.
A Kerr-type non-linearity widely encountered in optical media is included in the metal response and dipole-dipole coupling between nanoparticles is considered.
In the case of a nano-dimer, after studying the nature of nonlinear solutions as well as their stability, we have highlighted the emergence of rich and complex dynamics, and we studied in particular the appearance of chaos.
Although it appears to be random, it occurs in a nonlinear deterministic system under deterministic conditions.
The existence of the familiar chaos-leading period-doubling route is reported, and the domains corresponding to the occurrence of period-doubling and chaos in the parameter plane are evidenced.
In the case of a unidimensional metal nanoparticle chain, the mechanism of Modulational instability, which is responsible for the exponential amplification of low disturbances and which is due to the non-linearity of the metal, has allowed us to observe several spatiotemporal dynamics.
The Lyapunov spectrum allowed us to identify the observed complex behavior as spatiotemporal chaos.
We have shown that in the highly nonlinear regime, the spatiotemporal chaos is robust and exists in a wide range of parameters. Keywords : Nonlinear plasmonics,Nonlinear dynamics,Chaos,Kerr nonlinearity