Student Kilowatt-class ultrashort pulse laser with mJ pulse energy based on disk laser multipass amplifierTuesday (23.06.2020) 14:40 - 15:00 Room 1
Ultrashort pulse laser sources have become an important tool for many applications in microfabrication, such as microdrilling, cutting of transparent materials or surface nano-manipulation. Some applications are currently limited by slow processing times as a result of limited available pulse energy and output power. Higher power can lead to higher throughput and create economic viability for further material processing applications. One example is Direct Laser Interference Patterning (DLIP), which produces hierarchical micro- and nanostructures on surfaces . Another example of an application that profits from high pulse energy is glass cleaving. In a previous publication, 30 mm thick borosilicate glass has been permanently modified in a single pass modification process at a constant feed rate of 100 mm/s with a 1 kW, 7.5 mJ laser beam .
We present an amplifier for ultra-short pulsed lasers based on the disk laser technology which allows power scaling without change of beam characteristics. The laser system consists of a commercial TRUMPF TruMicro seed laser and one or several disk-laser based multipass amplifier stages. The seed laser with a pulse length of 1 ps or less and M²<1.1 is amplified to several mJ pulse energy and >1 kW average power with unchanged pulse length and beam quality. The flexibility of the seed laser, such as choice of repetition rate, pulse length, and bursts is maintained. An average output power of 1.9 kW and a pulse energy of 11.7 mJ have been demonstrated in a previous publication . No chirped-pulse amplification (CPA) is necessary to achieve this result. The large beam radius on the disk of several millimeters keeps peak intensities limited and nonlinear effects play a minor role. CPA can be employed in order to increase the output pulse energy further.
The multipass amplifier consists of a disk laser head and a highly stable monolithic mirror array which multiplexes the beam onto the disk 18 times, or 36 times if the multipass amplifier is traversed twice and the input and output beams are separated by a polarizer.
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