Revealing fractal dynamics by dispersion tuning in a mode-locked fiber laser

Fractal dynamics was previously observed by tuning nonlinearity through pump currents in a mode-locked laser. Here we show that the fascinating fractal dynamics (the devil’s staircase) can also be accessed by tuning dispersion only. In this case, the fractal dimension is also the same as that of the devil’s staircase. Standard dispersion control via the cut-back methods is not precise enough to observe the fractal phenomena. A precise and readily dispersion tuning method through software control is thus proposed and confirmed by the numerical simulations. Third-order dispersion is later considered and does not destroy the phenomena, confirming the robustness of the devil’s staircase. Our work confirms the universality of the fractal phenomena in mode-locked lasers, and that the numerical simulations could stimulate future experimental investigations.