@Workshop{Supelec493,
author = {Nicolas Marsal and Delphine Wolfersberger and Marc Sciamanna and Germano Montemezzani and Dragomir Neshev},
title = {{Etude des éffets d’un lattice optique sur un pattern hexagonal}},
year = {2008},
booktitle = {{Journée DYCOEC}},
month = {Feb},
address = {Nice (France)},
url = {http://www.coria.fr/dycoec/spip.php\'earticle44},
abstract = {Periodic photonic structures enable novel possibilities for manipulation of the fundamental aspects of wave propagation including enhancement of optical nonlinearity and control of light emission and radiation. The interplay between nonlinearity, optical gain, and bandgap effects gives rise to new physical phenomena on control of nonlinear dynamics and spatial pattern formation. This has inspired recent interest in dissipative discrete systems leading to the prediction of localised structures or bandgap manipulation of modulational instability. Despite the strong theoretical activities, experimental studies of such phenomena are lacking. In this work, we present what is to our knowledge the first experimental observation of band-gap manipulation of modulational instability in a periodic nonlinear dissipative system. We use a setup based on a photorefractive BaTiO3 crystal in a single feedback mirror configuration giving rise to hexagonal pattern formation. Additionally, we impose a square optical lattice to induce a two or one-dimensional photonic band-gap structure with variable parameters. We show that by varying the lattice strength and periodicity we can : induce patterns of square symmetry ; or suppress the modulational instability when the position of the lattice bandgap coincides with the instability gain. We also study how the threshold for modulational instability depends on the lattice strength and periodicity. We believe that similar manipulation of the nonlinear dynamics can also be potentially observed in lasers with large mode area and embedded photonic crystal structures. }
}