Experimental study and modeling of coexisting attractors and bifurcations in an erbium-doped fiber laser with diode-pump modulation

An all-fiber Erbium laser is shown to operate as a bistable nonlinear system under the control of harmonically modulated laser-diode pumping. We study a particular case where the pump modulation frequency is less than the fundamental laser frequency and show that a rich variety of bifurcations and attractors appear. An analysis, both experimental and theoretical, of the laser dynamics shows that the existence of frequency-locked states (Arnold's tongues) is a characteristic feature of this laser. The observed generalized bistability is demonstrated with codimensional-one and codimensional-two bifurcation diagrams in the parameter space of the modulation frequency and amplitude that results in overlapping of the Arnold's tongues for different attractors. Depending on the modulation frequency, two different scenarios to chaos, through period doubling and quasiperiodicity, are observed with an increase in the modulation amplitude.