Observation of two-dimensional surface solitons in asymmetric waveguide arrays

We report on the experimental observation of two-dimensional surface waves localized at the edge or in the corner of femtosecond laser-written waveguide arrays in fused silica. Increasing the power of the input beam allows one to observe a clear transition from a linear diffraction pattern to localized nonlinear surface states, which can exist at the interface only above a certain power threshold. This constitutes the first ever experimental observation of two-dimensional nonlinear surface solitons in optics.