▎ 摘　　要

We report on a graphene-oxide (GO) passively Q-switched thulium-doped double-clad fiber laser with two-stage amplifiers that can deliver >70 W average power at similar to 1950.27 nm wavelength. The achieved highest average power is similar to 73 W, corresponding to similar to 1.5 mu s pulse duration, similar to 0.877 mJ pulse energy, and similar to 585 W peak power. To our best knowledge, this is the first high-power pulsed output by using passive method to generate Q-switched pulses, especially by using GO as the saturable absorber, paving the way toward practical application of GOSA in high power pulsed double-clad fiber laser system.