Multiple pulse passive mode locking in lasers with spectrally inhomogeneous gain

A new mechanism of formation of multiple pulse operation, multistability, and hysteresis in lasers with spectrally inhomogeneous gain media such as ion-doped glasses has been discovered. The multistability manifests itself as a dependence on the initial conditions of the number of pulses in the laser operation that is established after the transient process. It has been found that the dependence of the number of pulses in the established operation on the pumping power is hysteretic in character. The mechanism revealed is connected with a change in the frequency dispersion of the active medium caused by the spectrally inhomogeneous saturation of the gain. Analysis and numerical simulation have been carried out on the basis of the modified Ginzburg-Landau equation, which takes into account the change in the spectral profile of the gain during laser operation.