Light propagation in non-linear and disordered photo-induced lattices

We present the first experimental results of our new non-linear optics lab at Universidad de Chile. We use photorefractive SBN crystals to photoinduce lattices of various geometries (square, hexagonal, Kagome, disordered, etc.), using a 532nm cw laser and spatial light modulators in real and Fourier space. In regular lattices, linear propagation of a focussed probe wave results in typical discrete diffraction patterns, with intense outer lobes expanding ballistically. Beyond the first Brillouin zone and the Bragg-reflection planes, we observe propagation in the second band. For an intense probe beam, the propagation entails a focussing non-linearity which can overcome diffraction and we observe the formation of continuous as well as discrete solitons. A wide input beam, on the other hand gets destabilized by modulational instability. Finally, in disordered landscapes, we study the Anderson Localization of light waves in 2D. The disorder-induced localization is strongly affected by the correlation properties of the disorder, as well as the spectral content of the probe beam.