Tm:fiber CPA driven nonlinear pulse compression stage delivering multi-GW, sub-10 fs pulses at 20 W of average power

We report on the generation of 102 mJ-, sub-2 cycle pulses with several GW of peak power centered at 1.73 mm wavelength. The intense few-cycle source features 8.8 fs pulse duration (full-width at half maximum, FWHM). It is operated at 196 kHz pulse repetition rate and provides a record average power of 20 W. This result is enabled by the combination of two average power scalable concepts: direct emission from an ultrafast Tm-doped fiber laser system and nonlinear pulse compression in a gas-filled antiresonant hollow-core fiber. Ultrafast Tm-doped fiber lasers are scalable to kW-level average power, which emphasizes the great potential of this approach for driving high cut-off HHG at high repetition rates.