Nonlinear phenomena in erbium-doped lasers

The nonlinear dynamics of an erbium-doped fiber laser is explained based on a simple model of the ion pairs present in heavily doped fibers. The single-mode laser dynamics is reductible to four coupled nonlinear differential equations. Depending on the ion-pair concentration, the pumping level and the photon lifetime in the laser cavity, numerical calculations predict cw, self-pulsing and sinusoidal dynamics. The regions of these dynamics in the space of the laser parameters are determined.