Abstract

High-power fiber lasers are being actively developed and now widely used in industrial welding and cutting processes. The most successful fiber laser, Yb-doped silica fiber laser, has a problem getting high efficient operation due to the photo-darkening (PD) effect. Chavez et al. [1] concluded that PD is generated by such valence state changes in Yb as from Yb³⁺ to Yb²⁺ and that Yb-Yb clusters might support such valence change phenomena. Researches on additive effects have also been reported that phosphorous and cerium additives effectively reduce the PD effect in Yb-doped silica fiber [2, 3]. Lee et al. presented another solution to suppress PD by preventing Yb-Yb clustering in a fiber material using phosphate glass [4].

© 2013 IEEE