In developing innovative fiber laser systems, the analysis of optical parameters such as average power, absorption of pump power, the optical spectrum, the pulse form and repetition frequency are important for characterizing and optimizing the systems.
With high-performance fiber lasers, mode instability occurs above a specific power. This means that the laser no longer emits in the transverse basic mode but displays a temporal dynamic in the transverse power distribution. The behavior prevents further power scaling and results in a poor beam quality of the laser.
To suppress undesirable effects in applications, the laser systems and modulation instabilities (e.g. beam quality) are analyzed at Fraunhofer IOF. On the basis of a detailed analysis, innovative fiber, pump and laser designs for suppressing mode instabilities and thus for further power scaling of high-performance fiber laser systems can be developed.
Tino Eidam, Christian Wirth, Cesar Jauregui, Fabian Stutzki, Florian Jansen, Hans-Jürgen Otto, Oliver Schmidt, Thomas Schreiber, Jens Limpert, and Andreas Tünnermann, »Experimental observations of the threshold-like onset of mode instabilities in high power fiber amplifiers«, Opt. Express 19, 13218-13224 (2011)