Divided-pulse nonlinear compression in a multipass cell

Yb:fiber-based pulses are split into 4-pulse bursts, sent into a gas-filled multipass cell for nonlinear pulse compression and recombined again to scale the supported output peak power and pulse energy. The pulse division and recombination are passively stable, being based on birefringent crystals, and enable a final output pulse energy of 3:4mJ at 32 fs pulse duration. Distributing the input energy over a 4-pulse burst allowed to work a factor two above the limitations of single-pulse operation regarding the occurrence of laser induced damage on the multipass cell mirrors. Overall, good efficiency, beam quality and temporal contrast are achieved.