High-energy ultrafast thin-disk oscillators

We have studied experimentally and numerically the pulse shaping dynamics of a diode-pumped thin-disk laseroscillator with active multipass cell and large output coupling rates. We demonstrate the generation of highenergy subpicosecond pulses with energies of up to 25 .9 µ J and durations of 928fs directly from a thin-disklaser oscillator without further ampli“cation. We have achieved these results by employing a sel“maging activemultipass geometry in order to increase the output coupling rate for a suppression of nonlinear optical eects.With this system we have obtained stable single pulse operation in ambient atmosphere with average outputpowers above 76W at a repetition rate of 2 .93MHz. A semiconductor saturable absorber mirror was used tostart and stabilize passive soliton mode locking. The experimentally studied laser pulses show good agreementwith numerical simulations including the appearance of Kelly sidebands. We present a modi“cation to thesoliton area theorem that is applicable for such a laser oscillator with active multiple pass cell and large outputcoupling rate. While numerically simulating the laser, we also investigated the intracavity pulse dynamics withinone round-trip and limitations for power scaling. Furthermore, we demonstrate the lasers potential for micromachining applications by showing “rst examples of material processing, such as the determination of ablationthresholds and ablation rates for various materials.Keywords: (140.3480) Lasers, diode-pumped; (140.3580) Lasers, solid-state; (140.4050) Mode-locked lasers