Shaping of amplified beam from a highly multimode Yb-doped fiber using transmission matrix

The transmission matrix of an ytterbium doped multimode fiber with gain was measured. It was shown to vary owing to the pump power level. Amplified beam focusing, beam steering and shaping were demonstrated using the measured matrix for input wavefront shaping, with an efficiency similar to the case of a passive fiber. The impact of weak gain saturation was lastly investigated. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement