Abstract

For constant Yb inversion and to increase pump power in the fiber core, a strong acceleration of the photodarkening (PD) process and a reduction in PD loss have been observed. The PD parameters determined by fitting the measured curves with the stretched exponential function are linked to the activation and deactivation rates of micro-optic centers (PD complexes). A phenomenological model is shown to reasonably describe the combined effect of Yb inversion and a direct influence of the pump power on these rates. It also offers the possibility of extrapolating the PD parameters to yield higher powers in the core of Yb fiber lasers.

© 2019 Optical Society of America

Linkage of photodarkening parameters to microscopic quantities in Yb-doped fiber material

Ulrich Röpke, Sylvia Jetschke, and Martin Leich
J. Opt. Soc. Am. B 35(12) 3126-3133 (2018)

Temperature influence on the photodarkening kinetics in Yb-doped silica fibers

Martin Leich, Sylvia Jetschke, Sonja Unger, and Johannes Kirchhof
J. Opt. Soc. Am. B 28(1) 65-68 (2011)

Deactivation of Yb³⁺ ions due to photodarkening

S. Jetschke, A. Schwuchow, S. Unger, M. Leich, M. Jäger, and J. Kirchhof
Opt. Mater. Express 3(4) 452-458 (2013)

Photodarkening in Yb doped fibers: experimental evidence of equilibrium states depending on the pump power

Sylvia Jetschke, Sonja Unger, Ulrich Röpke, and Johannes Kirchhof
Opt. Express 15(22) 14838-14843 (2007)

Efficient Yb laser fibers with low photodarkening by optimization of the core composition

Sylvia Jetschke, Sonja Unger, Anka Schwuchow, Martin Leich, and Johannes Kirchhof
Opt. Express 16(20) 15540-15545 (2008)