@InProceedings{Supelec586,
author = {Nicolas Marsal and Delphine Wolfersberger and Marc Sciamanna and Germano Montemezzani},
title = {{Advection effect in a photorefractive single feedback system: from noise- to dynamics- sustained instabilities}},
year = {2010},
booktitle = {{Proceedings of SPIE}},
volume = {7728},
month = {apr},
address = {Bruxelles (Belgique)},
abstract = {Systems in which intrinsic noise is amplified so that it
influences the system itself provide a way to probe and
characterize noise. In this work, we study the effect of
advection on an optical single feedback system displaying
patterns. This advection, occurring when the angle of the optical
pump beam is not zero gives rise to the so called convective
noise- and absolute dynamics- sustained instabilities. The
convective regime, where no pattern is expected, can show
structures or patterns if noise is present in the system.
Macroscopic noise-sustained structures can be formed resulting
from the amplification in preferential direction of the
perturbations produced by the microscopic noise. In contrast, in
the absolute regime the resulting optical pattern is sustained by
the drifting dynamics created by the advection.
Despite the large theoretical interest and recent experimental
demonstrations using a Kerr-type nonlinearity, an experimental
evidence of an advection effect on the dynamics of the pattern
formation process in a photorefractive system is still lacking.
We investigate experimentally and numerically the dynamics of
pattern excitation in presence of a tilted nonlinear
photorefractive single feedback system. By varying the angle of
the feedback mirror, thus breaking the inversion symmetry in the
system, we show that this advection effect causes the existence
of: (i) a transition from convective to absolute instabilities,
(ii) the formation of new pattern geometries, (iii) the seeding
of noise-sustained structures. To the best of our knowledge, this
last result is experimentally observed for the first time in an
optical system.
}
}