1 kW peak power, 110 ns single-frequency thulium doped fiber amplifier at 2050 nm.

We report a high power, single frequency, linearly polarized master oscillator power amplifier emitting 110 ns, 1 kW peak power pulses at 2050 nm. A 20% slope efficiency and a beam quality of M2=1.21 are achieved with three-stage double-clad Tm(3+)-doped fiber architecture.

Double-clad 10-W Yb3+-doped fiber master oscillator power fiber amplifier for He3+ optical pumping.

We describe an all-fiber ytterbium-doped laser followed by a double-stage ytterbium-doped double-clad fiber amplifier of 10-W output power for helium pumping. Different cavity designs are investigated with the goal of achieving high-power multimode emission at 1083 nm, wavelength tunability over the helium absorption bands, and linewidth envelope control over the range 1-3 GHz. We point out the domains with unstable output power and discuss their origin.