title: 600 W power scalable single transverse mode tapered double-clad fiber laser.
abstract: Pump propagation and absorption in active tapered double-clad fiber has been analyzed based on a ray optics approach. Optimization of the longitudinal shape, absorption and angular distribution of the pump beam allowed for power scaling of a ytterbium fiber laser up to 600 W with high beam quality (M2<or=1.08) and a slope efficiency of 63%. It is shown that the influence of vignetting in a tapered fiber can be avoided, resulting in high overall efficiency, in good agreement with the presented model.
authors.affiliation: Optoelectronics Research Centre, Tampere University of Technology, 33101 Tampere, Finland. valery.filippov@tut.fi
authors.forename: V
authors.initials: V
authors.lastname: Filippov
authors.forename: Y
authors.initials: Y
authors.lastname: Chamorovskii
authors.forename: J
authors.initials: J
authors.lastname: Kerttula
authors.forename: A
authors.initials: A
authors.lastname: Kholodkov
authors.forename: O G
authors.initials: OG
authors.lastname: Okhotnikov