  We study the formation and growth of laser-induced periodic surface
structures (LIPSSs) with the finite-difference time-domain (FDTD) method. We
use a recently proposed inter-pulse feedback method to account for the
evolution of the surface morphology between each laser pulse sent to the
surface of the processed material. This method has been used with an
ablation-like mechanism, by removing material exposed to a light intensity
higher than a given threshold. We propose an inverse mechanism, an
expansion-like mechanism, able to grow structures that the ablation-like
process cannot. This allows us to introduce the notions of constructive and
destructive feedback and explains a strong contradiction between the standard
Sipe-Drude theory and the experimental observations, i. e. the formation on
metals of structures usually linked to wide band gap dielectrics.
