Optical patterns in linear and ring photorefractive oscillators: From rolls to rotating flowers

Summary form only given. We present experimental and theoretical results on the diversity of pattern formation in linear and ring photorefractive oscillators. In a linear oscillator with plane parallel mirrors pumped by counterpropagating beams we observe both periodic patterns (rolls, rhomboids, tiles) and more complex irregular structures. When the cavity is detuned from the pump radiation, so that on-axis emission is suppressed, periodic patterns are dominant. When the tuning is adjusted to bring the cavity on resonance irregular dynamic structures are seen.