Spiral waves in a class of optical parametric oscillators - art. no. 055202

The formation of three-armed rotating spiral waves is shown to occur in a s patially extended nonlinear optical system with broken phase invariance. Th ese new spatial structures are found in the mean-field model of a class of optical parametric oscillators (3 omega --> 2 omega + omega) in which the m ultistep process 2 omega = omega + omega breaks the phase invariance of the down-conversion process. A parametrically-forced Ginzburg-Landau equation is derived to explain the existence of phase-armed spiral waves.