RESUMEN
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.
RESUMEN
We have observed the nonstationary polarization modulation of a speckle pattern transmitted through a photorefractive crystal under the alternating electric field of a square-wave form. A simple model based on Gaussian-beam propagation in the crystal with the diffusion type of nonlinearity is proposed to explain the main features of the experiment. Application of the phenomenon to noncontact and highly sensitive measurements of a rough surface movement is suggested.