Femtosecond laser direct nanostructuring of ion doped porous dielectric and semiconductor films: mechanisms and applications
Résumé
Femtosecond laser provides unique possibilities of the direct nanostructuring of both surfaces and highly localized volumes of dielectric materials. Here, we show extraordinary capacities of these lasers to create various surface and volume structures and to change their colors in mesoporous ion-doped matrixes.
In addition to wide band gap dielectric materials, ion-impregnated semiconductor materials are used. Our experiments are performed by using several laser systems, configurations and beams. Firstly, two-beam interference set-up was used to produce grating-like structures. Secondly, a single scanning laser beams was used to produce periodic surface nanostructures. The roles of laser fluence, wavelength and polarization direction are evidenced.
To better understand the mechanisms involved, a detailed multi-physical modeling is performed. Simulation results allow us to determine nanoparticle growth rate that relies not only on nanoparticle absorption, but also on the heat diffusion, photo-oxidation, and other reactions. The main laser parameters determine if the main mechanism is a thermal-activation or a photo-activation. Finally, the related applications in optics, photonics, catalysis and medicine are discussed.