Reduced-symmetry two-dimensional solitons in photonic lattices
  We demonstrate theoretically and experimentally a novel type of localized beams supported by the combined effects of total internal and Bragg reflection in nonlinear two-dimensional square periodic structures. Such localized states exhibit strong anisotropy in their mobility properties, being highly mobile in one direction and trapped in the other, making them promising candidates for optical routing in nonlinear lattices. 
Robert Fischer, Denis Traeger, Dragomir N. Neshev, Andrey A.   Sukhorukov, Wieslaw Krolikowski, Cornelia Denz, and Yuri S. K...