Fig. 1. Schematic diagram of the pulsed narrow-linewidth fiber laser

Fig. 2. Efficiency and SBS threshold power as a function of fiber length

Fig. 3. Backscattering light power varies with output power

Fig. 4. Laser output power as a function of the pump power

Fig. 5. Spectrum of the laser at the output power of 142 W

Fig. 6. Beam quality of output laser

Fig. 7. Pulse shape at the maximum output power（a）pulse width；（b）pulse repetition

Fig. 8. PER at different output power