Intensity spiral patterns in a semiconductor microresonator

Spiral waves appear frequently in nature. They have been studied, e.g., in hydrodynamic systems, chemical reactions, and in a large variety of biological and physical systems [Grill , Phys. Rev. Lett. 75, 3368 (1995); Goryachev and Kapral, Phys. Rev. Lett. 76, 1619 (1996)]. In contrast to chemical and hydrodynamic processes where the field amplitude exhibits the spiral patterns (intensity spirals), in optics the spiral structures relate generally to the phase structure of the optical field (so-called "optical vortices" [Lugiato , Adv. At., Mol., Opt. Phys. 40, 229 (1999); Arecchi , Phys. Rep. 318, 1 (1999); Weiss , Appl. Phys. B:Lasers Opt. B68, 151 (1999)]). Thus the question arises whether amplitude spiral patterns can exist also in optics. In [Lodahl , Phys. Rev. Lett. 85, 4506 (2000)] the existence of such spiral patterns in optics was theoretically predicted. Experimentally, intensity spiral patterns were shown to exist in an optical feedback system with radially symmetric excitation intensity [Huneus , Appl. Phys. B:Lasers Opt. B76, 191 (2000)]. We show here that such spiral patterns occur in a widely studied system, the semiconductor microcavity. The pattern formation is influenced here by the phase- as well as the intensity structure of the exciting light field.