Two-dimensional chiral splitting grating

This paper proposes a two-dimensional chiral splitting grating (CSG) based on chiral metasurfaces to combine beam-splitting with polarization selectivity. G-shaped silicon chiral units are introduced to achieve strong circular dichroism ( CD = 0.76). Using geometric phase theory and a simulated-annealing phase optimization method, a 21 × 21 binary (0/π) pure-phase CSG is designed. Simulations show that it generates a uniform 3 × 3 far-field spot array with 43.4% diffraction efficiency, 5.7% intensity uniformity, and 0.42 transmitted circular dichroism. This design merges the multi-beam splitting capability of Dammann gratings with chiral-based polarization control and suggests potential uses in optical computing, vector field generation, and information encryption.