High average power, high energy femtosecond regenerative amplifiers

Femtosecond lasers gain increasing interest because of the unique combination of ultrashort pulse duration and extreme high peak power on the GW-level. In consequence, the machining process is dominated by multiphoton processes making it essentially universal and almost any type of material can be machined with excellent precision and quality. In this paper we report on Yb-doped crystal based laser sources with ultra short pulse duration of a few 100 fs, high energies of several 100 µJ, and high average power of up to several 10 W.