Müller, M.M.MüllerBuldt, J.J.BuldtStark, H.H.StarkGrebing, C.C.GrebingLimpert, J.J.Limpert2022-03-062022-03-062021https://publica.fraunhofer.de/handle/publica/26793910.1364/OL.425872A multipass cell for nonlinear compression to few-cycle pulse duration is introduced composing dielectrically enhanced silver mirrors on silicon substrates. Spectral broadening with 388 W output average power and 776 µJ pulse energy is obtained at 82% cell transmission. A high output beam quality (M2<1.2) and a high spatio-spectral homogeneity (97.5%), as well as the compressibility of the output pulses to 6.9 fs duration, are demonstrated. A finite element analysis reveals scalability of this cell to 2 kW average output power.enaverage output powerCell transmissionsfew-cycle pulsemultipass cellNonlinear compression620535journal article