  Unlike traditional fiber laser with defined resonant cavity, random fiber
laser (RFL), whose operation is based on distributed gain and feedback via
Rayleigh scattering and stimulated Raman scattering in long passive fiber, has
fundamental scientific challenges in pulsing operation for its remarkable
cavity-free feature. Here, we propose and experimentally realize the passively
spatiotemporal gain modulation induced self-started stable pulsing operation of
counter-pumped RFL. Thanks to the good temporal stability of employed pumping
amplified spontaneous emission source and the superiority of this pulse
generation scheme, stable and regular pulse train can be obtained. Furthermore,
the pump hysteresis and bistability phenomena with the generation of high order
Stokes light is presented and the dynamics of pulsing operation is discussed.
This work extends our comprehension of temporal property of RFL and provides an
effective novel avenue for the exploration of pulsed RFL with structural
simplicity, low cost and stable output.
