title: High power tandem-pumped thulium-doped fiber laser.
abstract: We propose a cascaded tandem pumping technique and show its high power and high efficient operation in the 2-μm wavelength region, opening up a new way to scale the output power of the 2-μm fiber laser to new levels (e.g. 10 kW). Using a 1942 nm Tm(3+) fiber laser as the pump source with the co- (counter-) propagating configuration, the 2020 nm Tm(3+) fiber laser generates 34.68 W (35.15W) of output power with 84.4% (86.3%) optical-to-optical efficiency and 91.7% (92.4%) slope efficiency, with respect to launched pump power. It provides the highest slope efficiency reported for 2-μm Tm(3+)-doped fiber lasers, and the highest output power for all-fiber tandem-pumped 2-μm fiber oscillators. This system fulfills the complete structure of the proposed cascaded tandem pumping technique in the 2-μm wavelength region (~1900 nm → ~1940 nm → ~2020 nm). Numerical analysis is also carried out to show the power scaling capability and efficiency of the cascaded tandem pumping technique.
authors.forename: Yao
authors.initials: Y
authors.lastname: Wang
authors.forename: Jianlong
authors.initials: J
authors.lastname: Yang
authors.forename: Chongyuan
authors.initials: C
authors.lastname: Huang
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Luo
authors.forename: Shiwei
authors.initials: S
authors.lastname: Wang
authors.forename: Yulong
authors.initials: Y
authors.lastname: Tang
authors.forename: Jianqiu
authors.initials: J
authors.lastname: Xu