title: Increasing spatial complexity toward near-resonant regimes of quadratic media.
abstract: Near-resonant conditions lead to a strong interaction between saddle node and modulational instabilities in diffractive optical frequency down-conversion systems. The study of such an interaction reveals a new type of stable phase-locked mixed-mode hexagonal structure below the lasing threshold. Without this interaction, hexagonal structures do not exist. The analytical expression of the threshold associated with these structures is derived. Numerical solutions of the governing equations are in close agreement with analytical predictions.
authors.affiliation: Optique Nonlinéaire Théorique, Université Libre de Bruxelles, Campus Plaine CP 231, B-1050 Bruxelles, Belgium.
authors.forename: Mustapha
authors.initials: M
authors.lastname: Tlidi
authors.forename: Majid
authors.initials: M
authors.lastname: Taki