Observation of discrete solitons in lattices with second-order interaction

We present what we believe to be the first experimental demonstration of discrete solitons under the influence of first- and second-order lattice site interaction in zigzag femtosecond laser-written waveguide arrays. We show how the formation of these entities is affected by different ratios of the interaction strength. Increasing the second-order coupling between the lattices sites yields an almost linear increase of the input power required for soliton formation. (C) 2009 Optical Society of America