Advection effect in a photorefractive single feedback system: from noise- to dynamics- sustained instabilities

International audienceAn experimental analysis of the dynamics of optical patterns emerging from a photorefractive two-wave mixing geometry is investigated. The dynamics appears in the system, when a tilted single feedback mirror gives rise to an advection-like effect. Depending on the nonlocal coupling (introduced by the tilting angle) between the two counterpropagating beams, the strength of the nonlocal response of the nonlinear photorefractive bulk medium and the distance mirror-crystal, we report on: the seeding of new pattern geometry, the inversion of pattern transverse phase velocity and the bifurcation from convective to absolute instabilities