TeraSurface - Research project

The generation of periodic, aperiodic and hierarchical surface structures by ultrashort laser pulses makes it possible to control and boost the optical, mechanical and chemical properties of the surface. The function generated by the structure strongly depends on the characteristic dimensions of the printed periodic pattern, within a spatial scale ranging from the nanometer to the micrometer. The applications are multiple, and range from optics to mechanics, including biology, chemistry and the environment domains. A key issue of a laser process is the capacity to link the resulting topography to the primary mechanisms. The study of the morphology of a structured surface, in relation to its function and the application, can be done by using optical phase quantitative microscopy, having the potential to interrogate in real time the topography, in addition of post-mortem high-resolution electron and ion microscopy by which the structural state can be probed. On the other hand, the emission of secondary terahertz (THz) radiation, following the excitation of a surface, can be used to study the fundamental charge transport mechanisms that are excited during the transformation processes of its morphology due to laser irradiation. The 'TeraSurface' project proposes a completely new approach, based on the coupling between the generation of secondary THz sources by surface excitation and quantitative optical and electron microscopy of the surface, to move towards an ultimate understanding of surface ablation mechanisms in connection with the patterns generated and their characteristic dimensions. The study aims at collecting a database which will be used to validate the current models on the mechanisms of surface structuring by ultrafast lasers, also in connection with the parameters of the laser pulse.