Toward the formation of crossed laser-induced periodic surface   structures
  The formation of a new type of laser-induced periodic surface structures using a femtosecond pulsed laser is studied on the basis of the Sipe-Drude theory solved with a FDTD scheme. Our numerical results indicate the possibility of coexisting structures parallel and perpendicular to the polarization of the incident light for low reduced collision frequency ($\gamma/\omega \lesssim 1/4$, where $\omega$ is the laser frequency). Moreover, these structures have a periodicity of $\Lambda \sim \lambda$ in both orientations. To explain this behavior, light-matter interaction around a single surface inhomogeneity is also studied and confirms the simultaneous presence of surface plasmon polaritons and radiation remnants in orthogonal orientations at low $\gamma/\omega$ values. 
Jean-Luc D\'eziel, Joey Dumont, Denis Gagnon, Louis J. Dub\'e, Sandra   Messaddeq and Youn\`es Messaddeq
physics.optics