title: High-speed modal decomposition of mode instabilities in high-power fiber lasers.
abstract: A high-speed mode analysis technique is required to gain fundamental understanding of mode instabilities in high-power fiber laser systems. In this work a technique, purely based on the intensity profile of the beam, is demonstrated to be ideally suited to analyze fiber laser dynamics. This technique, together with a high-speed camera, has been applied to the study of the temporal dynamics of mode instabilities at high average powers with up to 20,000 frames per second. These measurements confirm that energy transfer between the fluctuating transversal modes takes place in millisecond-time-scale.
authors.affiliation: Friedrich Schiller Universität Jena, Institute of Applied Physics, Albert-Einstein-Str. 15, 07745 Jena, Germany. fabian.stutzki@uni‑jena.de
authors.forename: Fabian
authors.initials: F
authors.lastname: Stutzki
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Otto
authors.forename: Florian
authors.initials: F
authors.lastname: Jansen
authors.forename: Christian
authors.initials: C
authors.lastname: Gaida
authors.forename: Cesar
authors.initials: C
authors.lastname: Jauregui
authors.forename: Jens
authors.initials: J
authors.lastname: Limpert
authors.forename: Andreas
authors.initials: A
authors.lastname: Tünnermann