Jauregui Cesar, Otto Hans-Jürgen, Stutzki Fabian, Jansen Florian, Limpert Jens, Tünnermann Andreas
Friedrich-Schiller-Universität Jena, Institute of Applied Physics, Abbe Center of Photonics, Albert-Einstein-Str. 15, 07745 Jena, Germany.
Opt Express. 2013 Aug 12;21(16):19375-86. doi: 10.1364/OE.21.019375.
Mode instabilities have quickly become the most limiting effect when it comes to scaling the output average power of fiber laser systems. In consequence, there is an urgent need for effective strategies to mitigate it and, thus, to increase the power threshold at which it appears. Passive mitigation strategies can be classified into intrinsic, which are related to the fiber design, and extrinsic, which require a modification of the setup. In order to evaluate the impact of mitigation strategies, a means to calculate its power threshold and predict its behavior is required. In this paper we present a simple semi-analytic formula that is able to predict the changes of the mode instability threshold by analyzing the strength of the thermally-induced waveguide perturbations. Furthermore, we propose two passive mitigation strategies, one intrinsic and one extrinsic, that should lead to a significant increase of the power threshold of mode instabilities.
