A 280 W high average power, single-frequency all-fiber nanosecond pulsed laser

We demonstrate an all-fiber single-frequency nanosecond laser with high peak/average power based on the master-oscillator power-amplification (MOPA) configuration. A single-frequency laser at 1 μm wavelength is externally modulated and a single-frequency pulsed seed laser with a pulse width of ∼6 ns and repetition rate of 10 MHz is built. Three stages of power amplifiers scale the single-frequency pulsed seed laser to an average/peak power as high as 280 W/4.6 kW without the onset of stimulated Brillouin scattering effects. Further increase of the output power can be expected by increasing the pump power and adding amplifier stages.