Controllable helical collapse caused by a nonlinearity-related Gouy phase shift

Helical filamentation of optical fields has gained significant attention due to its potential physical properties, complexity, and practicality. However, conventional methods of manipulating filament formation face a major challenge in achieving controllable helical filamentation. We propose a method to manipulate helical collapse based on a nonlinearity-related Gouy phase shift. This method is triggered by the nonlinear interaction between vector vortex beams and anisotropic Kerr media. It is uncovered that, in the absence of the vortex, the radially polarized beam can only form the multifilament at specific locations in a ${\mathrm{BaF}}_{2}$ crystal. Nevertheless, once the vortex is attached, the beam can rotate based on the multifilament. The direction and angle of the rotation can be controlled by varying the topological charge number of the vortex phase. In addition, spin-orbit coupling and a rotational nonlinear refractive phase shift are generated during the helical collapse process. Finally, the physical mechanism behind this helical collapse is illustrated by a nonlinearity-related Gouy phase shift. This research presents a different approach to controlling optical field collapse and filamentation, with potential applications in various fields, including optical communications, optical manipulation, and optical microprocessing.