ABSTRACT
This chapter focuses on surface structuring of metals with the direct femtosecond laser irradiation on metal surfaces. When a femtosecond laser pulse strikes a metal surface, the pulse energy will be absorbed by the electrons first through the inverse bremsstrahlung mechanism over a skin layer on the order of 10 nm thickness. Micro- and nanoscale surface structures produced by direct femtosecond laser ablation can be classified into the following categories: irregular nanostructures; laser-induced one-dimensional periodic and quasi-periodic subwavelength structures; and laser-induced two-dimensional periodic subwavelength structures. Hwang et al. have performed a comparative study of femtosecond laser-induced nanostructures on three noble metals under identical experimental conditions. The technique also demonstrates a substantial degree of non-linear physical effects occurring in the femtosecond laser nano-/microstructuring, for example, in the triangular structure formation process. In general, micro- and nanoprocessing of materials by a femtosecond laser is based on pulse ablation i.e. material ejection from the irradiated sample.
