High peak power large mode area all fiber pulse amplifier

A power fiber amplifier module consisting of two stage fiber amplifiers, whose fiber core diameters were 15 μm and 25 μm respectively, was presented. It can output 30 kW peak power with 300 μJ output energy, when the input pulsed signal is 10 ns in duration，1 Hz in repetition frequency, 0.3 nm in spectrum width, and 80 nJ in energy. The output pulse’s temporal characteristic was investigated. It is found that the output energy of the amplifier module is confined by stimulated Brillouin scattering（SBS）effect when the input pulse is narrow banded, and adopting the broadband pulse could improve the SBS threshold of the fiber amplifier．