Topological Origin of Polarization-Controlled Wavefront Modulation

Optical metasurfaces, composed of subwavelength nanostructures, offer a powerful tool for manipulating light-matter interactions with precise control over phase, amplitude, and polarization [1]. These systems enable arbitrary polarization control, multiplexing, and even single-shot polarimetry imaging [2–4]. Here, we present a topology-protected wavefront engineering mechanism in co-linear polarization channels by encircling a phase singularity in the eigen-parameter space. This approach exploits the full 2π phase discontinuity originating from a topologically protected polarization singularity. Using a dielectric linear retarder metasurface, we experimentally validate this concept of the co-polarized singular phase as a new form of wavefront control mechanism, fundamentally distinct from the conventional dynamical phase. Moreover, the concept can be seamlessly integrated with existing phase-addressing scheme to achieve arbitrary polarization conversion and complex polarization-multiplexing, thus revealing the topological origin of advanced wavefront modulation and offering new routes beyond conventional techniques.