Polychromatic dynamic localization in curved photonic lattices

Abstract

The broadening of a wave-packet can be suppressed as it propagates through a periodic potential. The first-order effect of this so-called dynamic localization has been seen in many different systems. Higher-order effects are now seen for the first time in an optical pulse guided along 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 field1,2,3. 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 diffraction4,5,6,7,8. Dynamic localization was also observed for Bose–Einstein condensates9, and could have a role in the spin dynamics of molecular magnets10. It has been predicated that dynamic localization will occur in multi-dimensional lattices at a series of resonances between lattice, particle and driving-field parameters1. However, only the first dynamic localization resonance in one-dimensional lattices has been observed in any physical system6,7,8,9. 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 sources11,12.