Passively Q-switched Yb-doped all-fiber ring laser based on SBS feedback

We report on a passively Q-switched Yb-doped all-fiber (YDF) ring laser based on stimulated Brillouin scattering (SBS) feedback in a 20-m single-mode fiber (SMF). The Q-switched pulses are generated from the Stokes pulses of SBS and amplified in the YDF. The 10-ns self-Q-switched pulses with ∼1  kW maximum peak power are obtained. The repetition frequency of the pulse train is tuned from 4 to 12.6 kHz by changing the pump power in the experiment. A bandpass filter inserted in the laser cavity was used to suppress the time jitter of the Q-switched pulses.