Müller, M.M.MüllerKlenkea, A.A.KlenkeaSteinkopff, A.A.SteinkopffShestaev, E.E.ShestaevTünnermann, A.A.TünnermannLimpert, J.J.Limpert2022-03-142022-03-142019https://publica.fraunhofer.de/handle/publica/40607410.1117/12.2509693We present a coherently-combined ultrafast fiber laser system consisting of four amplifier channels delivering 3.5 kW average power at 80 MHz repetition rate with a pulse duration of 430 fs FWHM and a close-to-diffraction-limited beam quality with an M2 < 1.2. The system incorporates a fully automated self-adjustment of the beam combination, allowing for a quasi-turn-key operation of the system. At the date of publication, this system delivers the highest average power reported from an ultrafast laser.en620conference paper