Numerical analysis of beam self-cleaning in multimode fiber amplifiers

Recent experimental results have reported the observation of beam self-cleaning or, more generally, nonlinear beam reshaping in active multimode fibers. In this work, we present a numerical analysis of these processes by considering the ideal case of a diode-pumped signal amplifier made of a graded-index multimode fiber with uniform Yb doping. Simulations confirmthat beam cleaning of the signal may take place even in amplifying fibers, in the absence of beam power conservation. Moreover, we show how the local signal intensity maxima, which are periodically generated by the self-imaging process, may influence the population inversion of the doping atoms, and locally saturate the amplifier gain. (C) 2022 Optica Publishing Group

Automated summary

Recent experiments have shown that beam self-cleaning or nonlinear beam reshaping can occur in active multimode fibers. This study numerically analyzes these processes by considering an ideal diode-pumped signal amplifier made of a graded-index multimode fiber with uniform Yb doping. Simulations confirm that beam cleaning can occur in amplifying fibers even without beam power conservation. Moreover, the study reveals how the locally generated signal intensity maxima from the self-imaging process can affect the population inversion of doping atoms and locally saturate the amplifier gain.