title: Modulated optical structures over a modulationally stable medium.
abstract: Evidence of modulated dissipative structures with an intrinsic wavelength in a nonlinear optical system devoid of Turing instability is given. They are found in the transverse field distribution of an optical cavity containing a liquid crystal light valve. Their existence is related to a transition from flat to modulated fronts connecting the unstable middle branch of a bistability cycle and either of the two stable uniform states. We first analyze the cavity in the limit of nascent bistability, where a modified Swift-Hohenberg equation is derived. This allows for a simple analytical expression of the threshold associated with the transition as well as the wavelength of the emerging structure. Numerical simulations show development of ring-shaped modulated fronts and confirm analytical predictions. We then turn to the full model and find the same transition, both analytically and numerically, proving that this transition in not limited to nascent bistability regimes.
authors.affiliation: Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, Université des Sciences et Technologies de Lille, F-59655 Villeneuve d'Ascq, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Durniak
authors.forename: Majid
authors.initials: M
authors.lastname: Taki
authors.forename: Mustapha
authors.initials: M
authors.lastname: Tlidi
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Ramazza
authors.forename: Umberto
authors.initials: U
authors.lastname: Bortolozzo
authors.forename: Gregory
authors.initials: G
authors.lastname: Kozyreff