Self-compression of 5-$\mu$m pulses in hollow waveguides

We experimentally and numerically investigate self-compression of pulses around 5 $\mu$m wavelength in a noble-gas-filled hollow waveguides. We demonstrate spectral broadening of multi-mJ pulses at 4.9 $\mu$m and associated pulse compression from 85 fs to 47 fs in the solitonic pulse compression regime. The self-compression resulted in sub-three-cycle pulses with 17 GW peak power in the 1-kHz pulse train. A numerical model is established and benchmarked against the experimental results. It allows further insights into the pulse compression process, such as scaling of the compression as a function of gas pressure and waveguide radius, and predicts pulse compression in sub-cycle regime for realistic input parameters.