135 W, 0.5 mJ, sub-30 fs pulses obtained by nonlinear compression of coherently combined fiber CPA

Coherent combination of multiple fiber amplifiers in a chirped-pulse-amplification system allows achieving mJ-class femtosecond pulses at unprecedented repetition rates. These pulses are used for post-compression in a noble-gas-filled hollow-core fiber. Sub-30 fs pulses with energies of up to 540 J and a peak power of more than 11 GW at a repetition rate of 250 kHz (135 W) are achieved. Such laser systems could boost the achievable photon flux in highharmonic generation and potentially foster novel experiments in multi-dimensional surfacescience studies as well as coherent soft x-ray generation.