Dynamic Generation of Spatially Variable Vector Beams Using Cascaded Moiré Metasurfaces.

Vector beams with spatially inhomogeneous polarization distributions have demonstrated potential in applications such as optical micromanipulation, high-resolution imaging, and high-capacity optical communications. Metasurfaces have emerged as a compact platform for generating vector beams. However, achieving continuous dynamic adjustment of polarization order and spatial position within the same device remains a challenge. This research proposes and validates a mechanism for multidimensional dynamic light field control based on cascaded metasurfaces. In this approach, the metasurface employs phase modulation and the Moiré effect to generate conjugate vortex beams under circularly polarized incident light. Under linearly polarized illumination, coherent superposition generates vector beams with tunable polarization order and controllable focal position. Different rotation parameters govern the polarization order and azimuthal focal position, with limited cross-influence over the investigated range. For polarization orders of 0-6 and lateral offsets up to 30 μ m , the main polarization topology is preserved and all target OAM purities exceed 75%. At larger offsets, aberrations reduce the purity, although the target mode remains dominant and the focusing efficiency stays above 67%. This research expands the degrees of freedom for high-precision reconstruction of complex dynamic light fields, providing support for optical applications such as multi-target optical trapping and dynamic light routing.