Periodic ripples produced by a scanning beam of a femtosecond Ti:sapphire laser

The formation of periodic ripples is reported under exposure in air of several solids (Ge, GaAs, W, steel, etc.) to a scanning beam of a femtosecond Ti:sapphire laser operating at wavelength λ = 810 nm. Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) characterization shows that the period of ripples at normal incidence of laser radiation lies in a sub-λ domain and depends on the nature of the solid. Ripples are oriented perpendicular to the plane of polarization of the laser beam. Their period is different under ablation of a solid in a liquid environment at otherwise equal conditions. The results are interpreted as an interference of the incident laser radiation with a surface electromagnetic wave induced in the solid. The examples are presented of sub-μm structures generated by intersection of several ripple arrays.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.