Ortac, B.B.OrtacLimpert, J.J.LimpertTünnermann, A.A.Tünnermann2022-03-032022-03-032007https://publica.fraunhofer.de/handle/publica/21344810.1364/OL.32.0021492-s2.0-34548088372We report on high-energy ultrashort pulse generation from a passively mode-locked ytterbium-doped large-mode-area photonic crystal fiber oscillator operating in the anomalous dispersion regime. In the single-pulse regime, the laser directly generates 880 mW of average power of sub-500 fs pulses at a repetition rate of 53.33 MHz, corresponding to a pulse energy of 16.5 nJ. Stable and self-starting operation is obtained by adapting the spot size at the saturable absorber mirror to the pulse evolution in the low-nonlinearity fiber. The approach presented demonstrates the scaling potential of fiber based short pulse oscillators towards the µJ-level.enMU-Mgenerationpulses620535journal article