title: Diode-pumped narrow linewidth multi-kilowatt metalized Yb fiber amplifier.
abstract: We investigate high brightness pumping of a multi-kilowatt Yb fiber amplifier in a bi-directional pumping configuration. Each pump outputs 2 kW in a 200 μm, 0.2 NA multimode fiber. Gold-coated specialty gain fibers, with a 17 μm mode field diameter and a 5 dB/m pump absorption, have been developed. The maximum fiber amplifier output power is 3.1 kW, limited by multimode instability, with 90% O-O efficiency and M2<1.15. The fiber amplifier linewidth is 12 GHz.
authors.forename: Charles X
authors.initials: CX
authors.lastname: Yu
authors.forename: Oleg
authors.initials: O
authors.lastname: Shatrovoy
authors.forename: T Y
authors.initials: TY
authors.lastname: Fan
authors.forename: Thierry F
authors.initials: TF
authors.lastname: Taunay