Surface-Distributed Twisted Beams Nonlinearly Induced by Nondiffracting Beams

We developed an experimental method for generating light-induced microstructures in the form of twisted beam bundles arranged across curved surfaces. These structures arise during the nonlinear propagation of aperiodically modulated nondiffracting beams and are formed without the need for a prefabricated lattice or a tilted probe beam. Anisotropic refractive index patterns are optically induced in a single-pass experiment using a photorefractive medium. Our observations reveal the simultaneous formation of discrete soliton and helicoidal beam bundles. Discrete solitons follow trajectories conforming to a hyperboloidal surface, whereas the inner moving components trace cylindrical paths, resulting in the formation of helicoidal waveguides. The number of beams and their spatial arrangement can be precisely controlled by tuning the order, scale, and modulation parameters of the input beam. Although the initial light field is confined to a single surface, nonlinear self-interactions enable the transition of light across one or more curved surfaces. Furthermore, variation in the input beam power offers an additional degree of control over the shape and geometry of these surfaces, allowing for the fine adjustment of the propagation dynamics and structure of the beam bundles.