Double-flat-top half-vortices and self-bound solitary wave billiards in cubic-quintic media with intermodal attraction

Abstract

We consider a bimodal light field envelope propagating in a bulk medium characterized by competing cubic and quintic nonlinearities. The subfields are coupled by a cross-phase modulation term and experience effective attraction. We find dynamically stable stationary states which have two distinct flat-top regions with different intensities. These solutions represent half-vortices, where the first and second components are essentially different and, in particular, carry different topological charges: zero for one component and nonzero for the other. The typical propagation of an unstable half-vortex leads to the splitting of the central vortex core into several fragments which quasielastically interact with the boundary of the flat-top region. This behavior is interpreted as a self-bound solitary wave billiard, where the emerging fragments are the billiard balls and the flat-top region is the dynamically deforming table.