High Average Power Picosecond Thulium-doped All-fiber Amplifier

We reported the demonstration of high average power picosecond thulium-doped fiber amplifier (TDFA) at 2 µm using chirped pulse amplification technique. Here, the seed laser of the TDFA is an all-fiber passively mode-locked thulium-doped fiber laser with a the pulse duration of 63ps, and a fundamental repetition rate of 44MHz. A long dispersion compensating fiber with large positive group velocity dispersion β
2
of 90 ps
²
/km at 2000 nm is selected to broaden the pulse duration. Then, after two-stage all-fiber amplifiers, we obtain an unsaturated maximum output power of 73.5 W with an optical-to-optical slope efficiency of 49.8% with respect to absorbed 793 nm pump power. The pulse duration is 200 ps, and the corresponding peak power is 8.35 kW. These results provide an excellent pumping source for the applications like mid-infrared supercontinuum generation, material processing, spectral imaging, and so on.