Open AccessPhysical origin of mode instabilities in high-power fiber laser systems
Author(s) -
César Jáuregui,
Tino Eidam,
Hans-Jürgen Otto,
Fabian Stutzki,
Florian Jansen,
Jens Limpert,
Andreas Tünnermann
Publication year - 2012
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.20.012912
Subject(s) - equilibrium mode distribution , optics , adiabatic process , physics , mode (computer interface) , fiber laser , optical fiber , scaling , mode volume , waveguide , power (physics) , radiation mode , laser , single mode optical fiber , polarization maintaining optical fiber , fiber optic sensor , computer science , quantum mechanics , operating system , geometry , mathematics
Mode instabilities, i.e. the rapid fluctuations of the output beam of an optical fiber that occur after a certain output power threshold is reached, have quickly become one of the most limiting effects for the further power scaling of fiber laser systems. Even though much work has been done over the last year, the exact origin of the temporal dynamics of this phenomenon is not fully understood yet. In this paper we show that the origin of mode instabilities can be explained by taking into account the interplay between the temporal evolution of the three-dimensional temperature profile inside of the active fiber and the related waveguide changes that it produces via the thermo-optical effect. In particular it is proposed that non-adiabatic waveguide changes play an important role in allowing energy transfer from the fundamental mode into the higher order mode. As it is discussed in the paper, this description of mode instabilities can explain many of the experimental observations reported to date.