Improved photodarkening resistivity in ytterbium-doped fiber lasers by cerium codoping.

We show that the photodarkening resistivity of ytterbium-doped fiber lasers can be greatly improved by cerium codoping. It is suggested that the coexistence of the redox couple Ce(3+)/Ce(4+) in the glass provides means for trapping both hole- and electron-related color centers that are responsible for the induced optical losses in Yb-doped fiber lasers.