Noise-Sustained Convective Structures in Nonlinear Optics

Evidence of noise-sustained patterns in nonlinear optical systems is given. They are found in passive optical cavities, filled by Kerr type nonlinear media, when the angle of incidence of the pump beam is not zero, in a regime of convective instability. These patterns arise as a macroscopic manifestation of dynamically amplified noise, with amplification factors of up to ${10}^5$. We characterize the difference between noise-sustained and deterministic patterns in terms of statistical properties of the field spectral intensity.