Enhanced optical absorptance of metals using interferometric femtosecond ablation

The enhanced optical absorptance in metals was recently demonstrated using femtosecond laser-induced surface structuring. This structuring was obtained by simply focusing the light to the sample surface. Here we demonstrate more efficient absorptance enhancement using interferometric ablation. This interferometric ablation technique produces deeper surface structures and, consequently, higher absorption than structures obtained by just focusing the light to the surface. We also show the measured reflectance spectra over visible region for unaltered and structured stainless steel and copper samples.