Ultrafast Laser Processing of Materials

Activities-challenges:​​ Bio-inspired​​ surface modification​​ and functionalization of solid surfaces​​ via ultrashort laser pulses​​ in various types of materials (i.e. semiconductors, metals, dielectrics, polymers),​​ investigation of surface micro/nano structure role on wetting, optical,​​ and​​ tribological applications.​​ Control of surface morphology with shaped ultrashort double pulses. Development of laser induced metasurfaces and investigation of the physical mechanisms that lead to laser induced surface structure formation.

Biomimetic laser processing

Wetting properties:​​ By applying ultrashort UV, VIS and IR laser pulses novel surface structures with sub-micron sized features are produced while the physical properties of semiconductor, dielectric and metallic surfaces are significantly modified. Developed methods include laser micro/nano surface structuring performed in different media, direct laser writing with variable laser polarization states and combination of those. Further control over the surface topology is achieved by proper functionalization of the 3D structures obtained with well-defined nanostructures.​​ The artificial surfaces developed by processing under ambient controlled gaseous environments or in ambient environment exhibit controlled dual-scale roughness, that mimics the complexity of hierarchical morphology of natural surfaces with exciting wetting properties (i.e. the Lotus leaf, Texas horned Lizard), comprising micro-conical structures decorated with nanometer sized protrusions. The biomimetic morphology attained gives rise to notable wetting properties when combined with methods of tailoring the surface chemistry.

Figure 1:​​ Wetting response and​​ SEM pictures of actual lotus leaf (left) and fs treated silicon (right) surfaces

Optical properties​​ Based on the concepts and underlying principles discovered in nature, an interdisciplinary field has been developed, aiming to design and fabricate​​ photonic​​ biomimetic structures. This capability comes as the outcome of the optimal combination of the ultrafast laser field and material properties that enable the production of features with sizes beyond the diffraction limit (i.e., nanoscale)​​ that can mimic the functionalities of cicada and butterfly wings. A prominent example is the formation of self‐organized subwavelength, laser‐induced periodic surface structures (LIPSS), which have been proven an important asset for the fabrication of nanostructures with a plethora of geometrical features.​​ With​​ precise​​ ultrafast laser processing we can produced high anti-reflective artificial glass surfaces and high absorbing metal and semiconductor materials​​ [1].​​ ​​