Highly regular laser-induced periodic surface structures (HR-LIPSS) have been fabricated on surfaces of Mo, steel alloy and Ti at a record processing speed on large areas and with a record regularity in the obtained sub-wavelength structures. The physical mechanisms governing LIPSS regularity are identified and linked with the decay length (i.e. the mean free path) of the excited surface electromagnetic waves (SEWs). The dispersion of the LIPSS orientation angle well correlates with the SEWs decay length: the shorter this length, the more regular are the LIPSS. A material dependent criterion for obtaining HR-LIPSS is proposed for a large variety of metallic materials. It has been found that decreasing the spot size close to the SEW decay length is a key for covering several cm² of material surface by HR-LIPSS in a few seconds. Theoretical predictions suggest that reducing the laser wavelength can provide the possibility of HR-LIPSS production on principally any metal. This new achievement in the unprecedented level of control over the laser-induced periodic structure formation makes this laser-writing technology to be flexible, robust and, hence, highly competitive for advanced industrial applications based on surface nanostructuring.

We report time-resolved studies using femtosecond laser pulses, accompanied by model calculations, that illuminate the difference in the dynamics of ultrashort pulsed laser ablation of different materials. Dielectrics are strongly charged at the surface on the femtosecond time scale and undergo an impulsive Coulomb explosion. This is not seen from metals and semiconductors where the surface charge is effectively quenched.

Fast electronic transport is investigated theoretically based on a drift-diffusion approach for different classes of materials (metals, semiconductors, and dielectrics) under ultrafast, pulsed laser irradiation. The simulations are performed at intensities above the material removal threshold, characteristic for the ablation regime. The laser-induced charging of dielectric surfaces causes a subpicosecond electrostatic rupture of the superficial layers, an effect which, in comparison, is strongly inhibited for metals and semiconductors as a consequence of superior carrier transport properties.

Charge-collector probe measurements have been performed to elucidate ion acceleration in laser-induced plasma plumes over a range of laser fluences important for pulsed laser deposition. The fundamental (1064 nm) or second (532 nm) harmonics of a Nd:YAG laser were used for ablation. The evolution of the time-of-flight ion signal from single-peaked to double-peaked and again to single-peaked with increasing laser fluence in the range of $2–25\hspace{0.5em}{\mathrm{J}/\mathrm{c}\mathrm{m}}^2$ has been followed. The analysis of the ion velocity distributions shows that increasing laser fluence results in the appearance of a portion of accelerated ions that can be recognized as an additional fast peak in the time-of-flight distribution. The dependencies of the ion signal on the target-to-collector distance, the background pressure, and the wavelength of laser radiation have been studied. The results are discussed from the viewpoint of the generation of a self-consistent ambipolar electric field (so-called double layer). The observed ion acceleration suggests that formation in the plume of a high-energetic electron tail due to absorption of laser radiation is responsible for the development of a double layer.