Observation of discrete gap solitons in binary waveguide arrays
  We report on the first experimental observation of discrete gap solitons in binary arrays of optical waveguides. We observe the soliton generation when the inclination angle of an input beam is slightly above the Bragg angle, and show that the propagation direction of the emerging gap soliton depends on the input power as a result of an inter-band momentum exchange. 
Roberto Morandotti, Daniel Mandelik, Yaron Silberberg, Stewart   Aitchison, Marc Sorel, Demetrios N. Christodoulides, Andrey...