Exploiting nonlinear spectral broadening in a 400 W Yb:YAG thin-disk multipass amplifier to achieve 2 mJ pulses with sub-150 fs duration

We present investigations on the extent of spectral broadening occurring during the propagation of laser pulses in a Thin-Disk Multipass Amplifier (TDMPA) with the aim to exploit this nonlinear effect for pulse compression. The demonstrated compression of 2.05 mJ-pulses to a duration of about 136 fs FWHM at an average power of 409 W and a peak power of 9 GW is in good agreement with numerical pulse propagation simulations. Our spectral broadening and compression scheme introduced additional losses below 2%, is scalable to average powers of >1 kW with multi-mJ pulses, and strongly enhances the capabilities of ultrafast TDMPAs towards shorter pulses and higher peak powers.