Ultrashort-pulsed laser material processing with high repetition rate burst pulses

Thanks to the past years' development efforts towards higher average power levels, higher repetition rates and, of course, improved robustness, ultra-short pulsed lasers have been able to enter more and more industrial 24/7-production areas. Despite some exceptions, where ultrashort-pulsed lasers with very high repetition rates are used to weld glass and other sensitive materials, the majority of industrial applications are related to material removal or the use of non-linear effects in transparent materials. An interesting feature of ultra-short pulsed lasers in MOPA-configuration is the so-called "burst" mode. It provides pulse-packages at nanosecond separation using programmable power slopes. Thus, the energy distribution of the pulses within a burst can be adjusted to the specific application task. Using burst pulses, laser-material-interaction is brought into a different regime, as subsequent pulses hit preconditioned material and plasma effects can be used effectively. Burst pulses can help optimizing surface quality and ablation rates of engraved structures simultaneously. For laser filamentation of transparent and brittle materials, burst pulses provide filaments lengths of several millimeters.