Limpert, J.J.LimpertLiem, A.A.LiemReich, M.M.ReichSchreiber, T.T.SchreiberNolte, S.S.NolteZellmer, H.H.ZellmerTünnermann, A.A.TünnermannBroeng, J.J.BroengPetersson, A.A.PeterssonJakobsen, C.C.Jakobsen2022-03-032022-03-032004https://publica.fraunhofer.de/handle/publica/20671510.1364/OPEX.12.001313We report on an air-clad large-core single-transverse-mode ytterbium-doped photo nic crystal fiber with a mode-field-diameter of 35 µm, corresponding to a mode-f ield-area of ~1000 µm2. In a first experiment this fiber is used to amplify 10-ps pulses to a peak power of 60 kW without significant spectral broadening due to self-phase modulation allowing for the frequency up-conversion of these pulses using narrow-bandwidth phase matched nonlinear crystals.enlaserfibernonlinear opticsfiber design and fabricationultrafast laser620621journal article