Amplification of nanosecond pulses to megawatt peak power levels in Tm^3+-doped photonic crystal fiber rod

We report amplification of sub-10-100 ns pulses with repetition rates from 1 to 20 kHz in a rod-type thulium-doped photonic crystal fiber with 80 μm core diameter. The rod is pumped with a 793 nm laser diode and produces the highest peak power at 1 kHz repetition rate with 6.5 ns pulse duration and more than 7 W average output power. This result exemplifies the potential of this fiber design to scale pulse peak powers and pulse energies to the megawatt and multi-millijoule range in the 2 μm wavelength regime.