Theoretical analysis of optical bistability in a CW-pumped erbium-doped fiber laser

A theoretical model that allows numerical simulations of optical bistability phenomena in CW-pumped erbiumdoped fiber lasers is presented. Results of the simulations match correctly with previous experimental data. In order to simulate this phenomenon, the population inversion and optical powers longitudinal distributions along the active fiber have been considered. If this fiber is long enough, it has been found that the transition between the non-lasing and the lasing states involves a dramatic redistribution of the population inversion along the active medium. This fact makes that non-lasing and lasing states constitute different enough initial conditions which determine different final responses to the same control parameter, that is to say, bistability. On the other hand, a theoretical justification is found for a previous experimental result which pointed out that the bistability range becomes reduced if an external signal is launched to the cavity. Finally, the bistability range width dependence on the active fiber length is analyzed.