Elliptical-basis vectorial metagrating for full-Stokes polarimetry and polarization-encoded communication

Polarized light represents a fundamental degree of freedom of electromagnetic waves, carrying rich vectorial information essential for applications ranging from polarimetric imaging to optical communication. Here, we propose a high-performance vectorial metagrating designed via a matrix Gerchberg–Saxton (GS) optimization algorithm. The design employs elliptical polarization bases with maximal mutual separation on the Poincaré sphere, enabling the selective routing of incident light into four distinct elliptical polarization channels with high discrimination robustness. Full-wave simulation results verify the high performance of the metagrating: a total diffraction efficiency for the eigen-polarization channels reaches 66%, and the zeroth-order power is suppressed to below 0.6% (suppression ratio R sup ≈90). The metagrating further exhibits excellent polarization selectivity, achieving a polarization extinction ratio of 15.46 dB. Based on this metagrating, we demonstrate full-Stokes polarimetry with a reconstruction error as low as 1.29%. Further, the integration of the metagrating in an optical communication system enables self-routed information transmission and, thus, allows fully randomized channel transmission order, thereby enhancing polarization-encoded, XOR-based secure communication. These results highlight the potential of the elliptical-basis vectorial metagrating as a compact, versatile, and high-dimensional platform for advanced polarization information processing.