Nonlinear temporal compression in multipass cells: theory

The use of multipass cells as a way to spatially homogenize self-phase modulation and distribute its accumulation over the propagation distance is analyzed in detail, with the aim to perform nonlinear temporal compression. In addition to the insertion of nonlinear media at specific locations in the cell, as already demonstrated, we also propose to fill the cell with a noble gas, as is done in hollow capillary-based setups. This makes the accumulation of B-integral continuous rather than discrete. In this case, analytical estimates for the B-integral per round trip and scaling rules are provided as a function of cavity geometry and gas parameters. Then, three-dimensional numerical simulations are performed to assess the spatiotemporal couplings in the output beam in various conditions. This model is checked against experimental data presented in the literature, and used to predict our proposed scheme performance. We believe that these techniques constitute a promising way to allow temporal compression at energy levels beyond 10 mJ, where capillary-based setups are difficult to implement.