Fig. 1. Schematic setup of nanosecond polarization-maintaining all-fiber amplifier system with high-peak power and narrow linewidth

Fig. 2. (a) Output power and pump power; (b) monitored backward power and output power

Fig. 3. Output of pulse shape. (a) Single pulse width; (b) pulse repetition cycle

Fig. 4. (a) Spectra of pulsed seed with pulse width of 2.8 ns and repetition rate of 1.59 MHz; (b) output signal spectra at 139 W with pulse width of 2.8 ns and repetition rate of 1.59 MHz

Fig. 5. (a) Output signal power after high power polarization beam splitter; (b) polarization extinction ratio at different pump power levels

Fig. 6. (a) Output beam quality (M2 factor) of output laser; (b) two dimensional beam profile