Complex spatio-temporal dynamics of optical parametric oscillators close to threshold

Spatially extended degenerate cw optical parametric oscillators are predict ed to display a rich variety of spatio-temporal dynamic behaviour in two tr ansverse dimensions. Typical examples are the dynamical scaling of phase do mains, randomly distributed cavity solitons, formation of spatial patterns and optical turbulence. In spite of recent encouraging experimental results , many of these features can be difficult to observe in real devices since they require input energies which are too large. Here we show that in the c ase of a higher finesse for the pump field than for the signal field, compl ex spatio-temporal phenomena move closer to the signal generation threshold thus making their experimental observation more feasible.