Spatially Varying Polarization‐Structured Optical Fields via Multi‐Focus Synthesis for Multidimensional Image Encryption

Abstract To expand the vortex beam manipulation dimensions and improve orbital angular momentum (OAM) holographic encryption security, a novel vortex structured light field featuring space‐variant polarization is presented. The space‐variant polarization beam unite the modulation of the phase, amplitude, and polarization of vortex beams. While enabling arbitrary amplitude modulation and beam shaping for vortex light fields, it also achieves arbitrary customization of the local polarization states within the vortex beam. More importantly, leveraging the multi‐dimensional cooperative control characteristics of structured light fields, an OAM holographic encryption system with polarization‐switching capabilities is developed. By dynamically switching the polarization states of space‐variant polarized structured light, the polarization channels of the holographic encryption system can be altered, ultimately enabling controllable reconstruction of image information. Experimental results demonstrate that this work extends the traditional vortex light field control dimensions to triple physical dimension (amplitude, polarization, and topological phase) and also establishes a polarized OAM multiplexing encryption channel. The system supports dynamic polarization reconstruction of images, significantly enhancing security and channel capacity.