Universal description of pattern formation in optical oscillators under bichromatic injection

Abstract

We study pattern formation in a complex Swift–Hohenberg equation with phase-sensitive (parametric) gain. Such an equation serves as a universal order parameter equation describing the onset of spontaneous oscillations in extended systems submitted to a bichromatic injection when the instability is toward long (transverse) wavelengths. Applications include two-level lasers and photorefractive oscillators. Under such an injection, the original continuous phase symmetry of the system is replaced by a discrete one and phase bistability emerges. This leads to the spontaneous formation of phase-locked spatial structures, such as phase domains and dark-ring (phase) cavity solitons. The stability of the homogeneous solutions is studied, and numerical simulations are made covering all the dynamical regimes of the model, which turn out to be very rich. Derivations of the rocked complex Swift–Hohenberg equation, using multiple scale techniques, are given for the two-level laser and the photorefractive oscillator.