Rogue waves in a mode-locked fiber laser

In this paper, the authors numerically demonstrate the generation of optical rogue waves (temporal pulses) in the mode-locked fiber laser. In particular the obtained pulses have huge peak amplitude and big energy. These pulses appear unexpectedly (chaotically) in the laser and then disappear without any trace. In agreement with the calculated statistical distribution their peak power can be as much as 6 times bigger than the significant wave height (given by the amplitude in oceanology, but the intensity in optics) and exceed by more than 13 times the maximum possible peak power of the stable soliton in this laser. Such freak pulses are quite rare events but at the same time their probability is much higher than Gaussian statistic would predict. Hence, the obtained freak pulses in the mode-locked fiber laser can be called rogue waves according to the definition. The formation mechanism of the observed rogue pulses in the laser can be defined as peculiar focusing process which is of nonlinear dissipative nature, does not require any specific initial conditions, and fundamentally differs from the known ones (in nonlinear systems) such as: multi-soliton collision, nonlinear focusing (taking into account the nonlinear influence) and breather solutions. Eventually the obtained rogue waves generation can be established as a novel operation regime of mode-locked fiber lasers.