Multipass cell for high-power few-cycle compression

A multipass cell for nonlinear compression to few-cycle pulse duration is introduced comprising dielectrically enhanced silver mirrors on silicon substrates. Spectral broadening with 388 W output average power and 776 {\mu}J energy obtained at 82% transmission. high beam quality (M2<1.2) a spatio-spectral homogeneity (97.5%) as well the compressibility of pulses 6.9 fs are demonstrated. Finite element analysis reveals scalability this 2 kW power.