1.5 mJ, 350 fs Spectral Broadening in a Gas-Filled Concave-Convex Multipass Cell

Spectral broadening and pulse compression with multipass cells was mostly demonstrated with concave-concave geometries. Typical multipass cells (MPC) have a concave-concave geometry (cav-cav), which has a limitation in excessive self-focusing, laser-induced mirror damage and gas ionization [1]. A different geometry of a concave-convex cell (cav-vex) can avoid some limitations, because there is no focus inside the cell. Those cells showed excellent performance with the solid-state broadening medium [3]. Concave-convex cells are promising for energy scaling and keeping the overall footprint for the setup small. Here we perform first experiments demonstrating this regime with the commercial 2 mJ Carbide laser from Light Conversion.