Dispersion engineering in nonlinear multipass cells for high-quality pulse compression.

A dispersion-engineered multipass cell operating in the enhanced frequency regime is presented. Through the use of dispersive cavity mirrors, the nonlinear interaction is reshaped resulting in a smoother broadened spectrum, which yields a significant improvement in compressed pulse quality. The 70 W average power output of an Yb:fiber laser at 50 kHz repetition rate is compressed from 205 fs to 32 fs with more than 96% of the energy contained in the temporal main feature of the pulse. This first, to the best of our knowledge, experimental demonstration of a pulse quality improvement through enhanced frequency chirping in a multipass cell displays the opportunities for dispersion-tailored pulse compression.

22-W average power high pulse energy multipass-cell-based post-compression in the green spectral range.

A gas-filled multipass-cell-based post-compression of 515 nm wavelength second-harmonic pulses of an Yb:fiber laser from 240 fs to 15.7 fs is presented. The system delivers 0.44 mJ of pulse energy, 22.4 W of average power at 50.8 kHz with an overall efficiency of more than 40%. These results display the capabilities of multipass-cell-based post-compression schemes to move from the well-established near infrared spectral region to the undeveloped visible regime, allowing for high efficiencies in conjunction with energetic ultrashort pulses at high repetition rates. The unique combination of parameters in the green spectral range offers an immense potential for future developments of high photon flux higher-order harmonic sources.