Passive Q-switching dynamics in SBS/Er fiber laser at low pump power

We report our experiments with Er-doped fiber lasers pumped by low-power 980 nm laser diode. The pulsation operational mode caused by the Rayleigh backscattering-SBS mechanism was successfully observed at pump power levels of 30-80 mW. Self-starting pulses generation occurred at a quite stable repetition rate in the range of 300-500 μs and peak power of 50-200 W with ~50% fluctuation. In contrast with previous experiments, the laser dynamics were simple and slower. Using a digital oscilloscope we could recognize different stages of the Q-switching pulse formation process and investigated each of them experimentally in detail