Liu, C.H.C.H.LiuEhlers, B.B.EhlersDoerfel, F.F.DoerfelHeinemann, S.S.HeinemannCarter, A.A.CarterTankala, K.K.TankalaFarroni, J.J.FarroniGalvanauskas, A.A.Galvanauskas2022-03-032022-03-032004https://publica.fraunhofer.de/handle/publica/20745910.1049/el:20046464It is shown that continuous-wave kW-power fibre lasers can be built using double-clad fibres with relatively small cores. 810 W in a single-transverse-mode Output (M-2 = 1.27) is demonstrated experimentally with 20 mum core low-NA (NA = 0.06) Yb-doped double-clad fibre. A laser numerical model matches experimental results and predicts scalability of achievable powers into a multi-kW range.en621671384journal article