Monolithic all-fiberized nanosecond laser with kilowatt average power and megawatt peak power

We demonstrate an all-fiberized less than 10 ns master oscillator power amplifier (MOPA) with an average power of more than 1 kW, pulse energy of -10 mJ, and peak power of -0.78 MW using pulse distortion and narrowing of 30 ns laser pulses as the seed beam. The effects of the pulse width of the seed laser and injected signal power on the pulse narrowing were investigated theoretically and experimentally. By simulations, we proved that a longer signal pulse width could be compressed more effectively than a pulse with a shorter width. Moreover, the increase of the injected power could promote the narrowing of the amplified pulse. Experimentally, the distortion and narrowing of 30 ns laser pulse can effectively improve the maximum output power free of nonlinear optical effects such as stimulated Raman scattering (SRS) of all-fiberized less than 10 ns amplifiers. We also found an optimal combination of the pumping and injected power to achieve a trade-off between the SRS and amplified spontaneous emission (ASE) to obtain the highest SRS-free output power and narrowest pulse width.