Directional Perturbation-Driven Independent Control of Orthogonally Polarized Phases in Metasurfaces

Independent control of the orthogonally polarized phase is fundamental to polarization-modulated metasurfaces. Here, we present a directional perturbation-driven strategy enabling independent control of orthogonally polarized phases in metasurfaces. By introducing a directional perturbation along the short axis of an anisotropic waveguide, the phase shift of the short-axis polarization can be independently regulated, while the phase shift of the orthogonal polarization is maintained. This perturbation also enhances electric field localizations, leading to superior optical efficiency. As a proof of concept, we demonstrate full Poincaré sphere waveplates and an anomalous refractive quarter waveplate. Our work advances the development of practical, high-efficiency polarization optics.