Modeling of the Laser Polarization as Control Parameter in Self-Organized Surface Pattern

Abstract

To shed light on nanopattern formation upon femtosecond laser ablation, an adopted surface erosion model is developed, based on the description for ion beam sputtering. In particular, the dependence of generated patterns on the laser polarization is taken into account. We find that an asymmetry in deposition and dissipation of incident laser energy results in a respective dependence of coefficients in a nonlinear equation of the Kuramoto-Sivashinsky type. Surface morphologies obtained by this model for different polarization of the laser beam are presented and the time evolution of the nanopattern is discussed. A comparison of these numerical results with experimental data shows an excellent agreement. Dependence of femtosecond laser induced formation on the polarization of the incident beam within an adopted surface erosion model is considered. A continuum theory of erosion by polarized laser radiation is developed. We exploit the similarity to ion-beam sputtering and extend a corresponding model for laser ablation by including laser polarization. This yields a respective dependence of coefficients in a nonlinear equation of the Kuramoto-Sivashinsky type. We present the surface morphologies obtained by this model for different polarization of the laser beam and discuss a time evolution of the nanopattern. These numerical results are in a good agreement with numerous experimental data. We show that the correlation of ripples orientation with laser polarization can be described within a model where the polarization causes the breaking of symmetry at the surface. Our results support the non-linear self-organization mechanism of pattern formation on the surface of solids.