Picosecond laser source at 3.4 microns for laser material processing of polymers

We present a laser beam source with average output powers of up to 15 W and pulse energies of up to 50 mJ at a wavelength of 3.4 mm based on a frequency converted ultrashort pulse laser. The laser beam source consists of a commercially available ultrashort pulse laser with a pulse duration of 10 ps and a downstream multi-stage optical parametric frequency converter based on large-aperture PPLN crystals. Different output powers, pulse energies, conversion efficiencies and beam qualities are achieved depending on the design of the multi-stage setup. In addition, we present some results of processing experiments on different polymer films obtained with the laser beam source presented here.