By increasing the Fresnel number F of a ring cavity with photorefractive gain, we show the transition between a low-F regime, where a few modes compete with a periodic alternation which becomes irregular with increasing F (chaotic itinerancy), and a high-F regime, where many modes oscillate simultaneously, giving rise to chaotic domains spatially correlated over a length much shorter than the wave-front size (spatiotemporal chaos).

• Received 6 August 1990

DOI:https://doi.org/10.1103/PhysRevLett.65.2531