Femtosecond-Laser Induced Nanostructures in TiO2

TiO2 nanostructures are important functional materials with a growing number of applications in fields like medicine, photochemistry or photovoltaics. We demonstrate that highly reproducible nanostructures can be generated on the surface of bulk as well as thin film material by exploiting the phenomenon of laser-induced periodic surface structures (LIPSS). The influence of key parameters like pulse number, laser fluence, wavelength, and surface quality on the formation of such nanoripples is discussed. The time-integrated theory of Drude and Sipe is extended by the nonlinear excitation of transparent materials into a transient metal-like state enabling for the effective generation of surface plasmon polaritons.