Work

Tunable rotational transverse multifoci generated by catastrophe fields with discrete phase and coordinate rotation

Year: 2026

Type: article

Abstract: Autofocusing structured fields have important potential in parallel optical manipulation and configurable focal field. However, it is still challenging to regulate the transverse multifoci array, as superimposed catastrophe fields tend to concentrate energy near the center or mainly exhibit longitudinal autofocusing. Here, we propose a transverse multifocal higher-order catastrophe field by engineering discrete phase on the constituent subfields. This strategy enables coplanar rotational multifocal arrays with tunable radius, focal spacing, focal width, and residual central intensity through the subfield number N and structural parameter C. We show that the transverse focusing pattern is governed by discrete phase symmetry: removal of the phase collapses the array into a single central focus, whereas prescribed discrete phase delays produce well-separated rotational arrays of foci. The design theory has been well corroborated by experiment using off-axis computer-generated holography. Phase, transverse energy-flow, and orbital angular momentum (OAM) analysis reveals orientation evolution, circulating transverse energy flow, and nonzero multimodal OAM without an externally imposed vortex phase. The established results suggest that the discrete subfield phase engineering can be considered as a universal strategy for tailoring rotational multifoci catastrophe fields, opening opportunities for structured-light engineering, parallel optical manipulation, and topological light-field design.

Source: Chaos Solitons & Fractals

DOI: 10.1016/j.chaos.2026.119134