Self-trapping of broad beams in defocusing nonlinear Lithium Niobate waveguide arrays

The coherent transport of nonlinear waves is essential in many phenomena in nature. In contrast to linear waves, the physics becomes complex when wave interactions start to play a role, making laboratory studies difficult. As such, many of the fundamental physical effects of nonlinear waves have been first studied in optics. The recent experimental developments in Bose-Einstein condensates (BEC) opened the way for many analogous experiments with intense sources of coherent matter waves. Our studies show for the first time that these novel types of spatially localized modes can have an arbitrary width defined by the input beam, while practically independent on nonlinearity.