Polychromatic dynamic localization in curved photonic lattices

Dynamic localization is the suppression of the broadening of a charged-particle wave packet as it moves along a periodic potential in an a. c. electric field(1-3). The same effect occurs for optical beams in curved photonic lattices, where the lattice bending has the role of the driving field, and leads to the cancellation of diffraction(4-8). Dynamic localization was also observed for Bose-Einstein condensates(9), and could have a role in the spin dynamics of molecular magnets(10). It has been predicated that dynamic localization will occur in multidimensional lattices at a series of resonances between lattice, particle and driving-field parameters(1). However, only the first dynamic localization resonance in one-dimensional lattices has been observed in any physical system(6-9). Here, we report on the experimental observation of higher-order and mixed dynamic localization resonances in both one- and two-dimensional photonic lattices. New features such as spectral broadening of the dynamic localization resonances and localization-induced transformation of the lattice symmetry are demonstrated. These phenomena could be used to shape polychromatic beams emitted by supercontinuum light sources(11,12).