title: Self-focusing and defocusing in waveguide arrays.
abstract: We show that two regimes of diffraction exist in arrays of waveguides, depending upon the input conditions. At higher powers, normal diffraction leads to self-focusing and to the formation of bright solitons through the nonlinear Kerr effect. By slightly changing the input conditions, light experiences anomalous diffraction and is nonlinearly defocused. For the first time, self-focusing and self-defocusing have been achieved for the same medium, structure, and wavelength.
authors.affiliation: Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel 76100.
authors.forename: R
authors.initials: R
authors.lastname: Morandotti
authors.forename: H S
authors.initials: HS
authors.lastname: Eisenberg
authors.forename: Y
authors.initials: Y
authors.lastname: Silberberg
authors.forename: M
authors.initials: M
authors.lastname: Sorel
authors.forename: J S
authors.initials: JS
authors.lastname: Aitchison