Transverse wave number selection and propagation of 2D-pulses in lasers with saturable absorber

Selection of transverse patterns in laser systems with an intra-cavity saturable absorber is shown to be tuned by the absorber. The wavelength of the selected pattern is theoretically predicted, and the prediction is in a good agreement with the results of the numerical solutions of the governing equations for a 2-level laser model. An interesting feature is that the presence of a saturable absorber leads to the formation of transverse patterns in regimes where the free-running laser exhibits only a stable homogeneous state, via a frequency-pulling phenomenon. A surprising threshold reduction effect may also be observed in this case. We also show that when the absorber inhibits structure formation, transverse propagating pulses may appear.