Femtosecond laser pulses in a Kerr lens mode-locked thin-disk ring oscillator with an intra-cavity peak power beyond 100 MW

We report 860 W average power, similar to 440 fs laser pulse generation inside a 15.2 MHz thin-disk ring oscillator under development for intra-cavity high-order harmonic generation (HHG). This has been achieved by placing a Kerr lens mode-locking setup in a low-pressure chamber. The intra-cavity pulse energy is similar to 57 mu J with an estimated peak power of 130 MW, which is the highest, to the best of our knowledge, in ring type oscillators. By focusing these laser pulses, we can expect a peak intensity high enough for demonstration of intra-cavity HHG at the multi MHz repetition rate to facilitate experiments in photoelectron spectroscopy. (C) 2014 The Japan Society of Applied Physics