Popp, A.A.PoppDistler, V.V.DistlerJaksch, K.K.JakschSedlmeir, F.F.SedlmeirMüller, C.R.C.R.MüllerHaarlammert, N.N.HaarlammertSchreiber, T.T.SchreiberMarquardt, C.C.MarquardtTünnermann, A.A.TünnermannLeuchs, G.G.Leuchs2022-03-062022-03-062020https://publica.fraunhofer.de/handle/publica/26335710.1007/s00340-020-07476-7We investigate the frequency-resolved intensity noise spectrum of an Yb-doped fiber amplifier down to the fundamental limit of quantum noise. We focus on the kHz and low MHz frequency regime with special interest in the region between 1 and 10 kHz. Intensity noise levels up to > 60 dB above the shot noise limit are found, revealing great optimization potential. Additionally, two seed lasers with different noise characteristics were amplified, showing that the seed source has a significant impact and should be considered in the design of high power fiber amplifiers.enfiber amplifierYtterbiumbeam qualityquantum noiseshot noise620621journal article