High energy nonlinear pulse compression to sub-50 fs by a hybrid bulk-air multi-pass cell

We demonstrate a high energy nonlinear pulse compression scheme based on a hybrid bulk-air multi-pass cell (MPC), achieving a high-power ultrafast source with 45 fs pulse duration, 130 W average power at 200 kHz repetition rate, and near-diffraction-limited beam quality. The impact of air nonlinearity accumulation in the MPC on beam quality is investigated to maintain good beam quality at high pulse energy, which suggests the adoption of pre-chirped and circularly-polarized pulses can effectively improve the input pulse energy and suppress the spatial quality degradation. The nonlinear mode-matching is also adopted to minimize the impact of the self-focusing effect of solid-thin-plates on q-preserving propagation. Although both solid plates and air contribute to the spectral broadening, the hybrid MPC is still an all-solid-state configuration without a pressure-controlled cell, providing a compact and economical approach for the nonlinear pulse compression at several hundred microjoules (µJ) energy levels. To the best of our knowledge, this is the highest pulse energy from the solid-state MPC configuration.