TRANSVERSE EFFECTS IN A LASER WITH AN INJECTED SIGNAL

We study the space-time behaviour of a single-longitudinal-mode laser in the presence of a small external signal, taking into account diffra ction effects. Combining analytical and numerical results we show that for negative detunings there is a bifurcation from the trivial soluti on to a spatially homogeneous steady state, while for positive detunin gs a travelling wave is realized. In both cases, the solutions are sup erimposed on a spatially homogeneous oscillation at the frequency of t he external field.