Direct laser processing of material surfaces is a powerful technique for modifying the optical and electrical properties of those materials, often through the creation of nanostructures on the surface. The precise control of those surface modifications, and hence of the material’s modified properties, has remained challenging, largely due to the element of random chance that influences the size and geometry of the small-scale-structures themselves.
Femtosecond lasers have offered a route to greater control over the operation, and to the creation of structures having sub-wavelength periodicity. But the ability to precisely design the resulting surface properties has remained elusive.
A project at the University of Rochester has now demonstrated a new way to influence the morphology of surface nanostructures, and hence the spectral light absorption of a treated metal. The work was reported in Light, Science & Applications.
The breakthrough could be directly useful in thermal-solar devices, boosting the efficiency of tungsten-based absorbers and improving their thermoelectric generation performance compared to untreated tungsten surfaces.