Open AccessThermally induced waveguide changes in active fibers
Author(s) -
Florian Jansen,
Fabian Stutzki,
Hans-Jürgen Otto,
Tino Eidam,
A. Liem,
César Jáuregui,
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.20.003997
Subject(s) - materials science , optics , reduction (mathematics) , refractive index , waveguide , optical fiber , equilibrium mode distribution , core (optical fiber) , radiation mode , fiber , single mode optical fiber , optoelectronics , composite material , physics , mathematics , geometry
Thermally induced waveguide changes become significant for very large mode area fibers. This results in a reduction of the mode-field diameter, but simultaneously in an improvement of the beam quality. In this work the first systematic experimental characterization of the reduction of the mode-field diameter in various fibers during high-power operation is carried out. It is shown that the reduction of the mode-field diameter shows a characteristic behavior that scales with the core size but that is independent of the particular fiber design. Furthermore, the strength of the actual index change is experimentally estimated, and its use to overcome avoided crossings is discussed and experimentally demonstrated.