title: Single-mode 212 W tapered fiber laser pumped by a low-brightness source.
abstract: With a tapered double-clad all-glass ytterbium fiber as a gain medium, a maximum output power of over 200 W at 1079 nm and a slope efficiency of over 70% were demonstrated. The tapered double-clad fiber concept allows for using low-brightness diode bars and results in cost-effective and efficient high-power fiber lasers. The adiabatic conical fiber gain waveguide combines improved pump absorption owing to enhanced mode mixing in the pump cladding, low-noise single fundamental mode operation with M(2)< or =1.02, and strong potential for significant power scaling.
authors.affiliation: Optoelectronics Research Centre, Tampere University of Technology, 33101 Tampere, Finland. valery.filippov@tut.fi
authors.forename: Valery
authors.initials: V
authors.lastname: Filippov
authors.forename: Yuri
authors.initials: Y
authors.lastname: Chamorovskii
authors.forename: Juho
authors.initials: J
authors.lastname: Kerttula
authors.forename: Artem
authors.initials: A
authors.lastname: Kholodkov
authors.forename: Oleg G
authors.initials: OG
authors.lastname: Okhotnikov