Influence of stimulated Brillouin scattering on the dynamics of a self-pulsing fiber laser

In the last few years several experimental and numerical results have been reported on the emergence of extreme events and instabilities in different laser configurations such as Raman fiber lasers, optically injected semiconductor lasers, laser diodes with optical feedback and mode-locked lasers [1-4]. Rogue events can however be expected in some of these systems due to the complex noise-driven processes intrinsically at the origin of laser operation. In some specific cases, the origin of the extreme events in dissipative laser systems have been attributed to nonlinear coupling between several longitudinal modes of the cavity [2] or to multiple pulses coexisting inside a mode-locked laser [3]. In this contribution, we report on the development of a numerical model to describe the dynamics of a self-pulsing ytterbium-doped fiber laser under the influence of stimulated Brillouin scattering. Our numerical simulations are based on a coupled amplitude model describing the spatio-temporal dynamics of the laser and Brillouin waves, as well as the temporal variation of the gain for each wave. An artificial saturable absorber effect has been included in the model to take into account signal reabsorption along the cavity. Our numerical model predicts irregular self-pulsing instabilities just above the laser threshold with pulse durations around 1 μs, as observed experimentally [5]. For high pump powers, the model predicts however the emergence of transient pulses with shorter durations, as in experiments [5]. The peak intensity and the occurrence of these nanosecond bursts increase with pump power thereby allowing to reach and exceed the rogue wave intensity level at high pumping levels. An example of temporal distribution including rogue pulses and its corresponding histogram are shown in Fig. 1. More details on the influence of the laser parameters as well as the impact of Kerr nonlinearities on the laser temporal dynamics will be discussed during the conference.