High peak power narrow-linewidth linearly polarized all-fiber nanosecond laser

An all-fiber laser is developed with high peak power, narrow linewidth,linearly polarization, and nanosecond pulse. The single-frequency continuous fiber laser is externally modulated by an electro-optical intensity modulator(EOIM) and a stable pulsed seed laser is obtained with the pulse width of 10 ns and the repetitions rate of 10 kHz. Multistage MOPA structure scheme is adopted.After two stages core-pumped preamplifiers and three stages cladding-pumped amplifiers, the average output power of the laser reach to 21.3W with the peak power of 267 kW. At the highest output power, the signalto-noise ratio of the spectral is greater than 30dB, the polarization extinction ratio is superior 15dB and the M_x² and M_y² factors are 1.28, 1.23, respectively. Stimulated Brillouin scattering (SBS) was not found in the experiment. By increasing the pump power, the average power and peak power can be further improved.