Second harmonic generation from two-dimensional gold nanorods of arbitrary shape: Numerical study.

The nonlinear optical properties of subwavelength patterned metallic structures have been recently re-analyzed. We developed a Green function based numerical method in order to calculate the second harmonic field pattern generated by a finite number of two dimensional single and double metallic rods of arbitrary shape. We modelled the optical response of Au considering contributions from both free and bound electrons. Thus we can assume that the nonlinear SHG effect in bulk is mainly due to the response of the conduction electrons. On the other hand, nonlinear surface effects are affected by both valence and conduction band electrons. Evaluation of the non linear second order response is done by considering the classical dynamic equation of the free electron gas. We study the SHG process in undepleted pump approximation from a metallic 2D structure which reacts in presence of a TM (p) polarized E.M. field; the system is completely bi-dimensional (2D).