Femtosecond Laser Processing of Soft Materials.

Abstract

Ablation of polymer films such as polyimide, polycarbonate, polyethylenterephthalate, polytetrafluoroethylene and polymethylmethacrylate were investigated with a Ti: sapphire laser system (150 fs, 800 nm). The single pulse threshold increased from 1.0 Jcm-2 of polyimide to 2.6 Jcm-2 of polymethylmethacrylate. This correlates with the increase of the optical band gap suggesting a multi-photon absorption mechanism. All polymers show incubation effects. A stronger incubation could be found for polycarbonate, polyethylenterephthalate, and polymethylmethacrylate in contrast to the "inert" polymers polyimide and polytetrafluoroethylene due to irreversible chemical alterations. All polymers except polyimide exhibited melting and the generation of vapour yielding swelling. Polyimide only sublimates and/or degrades. Ripples parallel to the electric field vector were generated with linear polarization of repeated laser pulses whereas circular polarization resulted in nanostructure arrays of the order of -100 nm.