Dual-function polarization-selective metagrating for electromagnetic wave control

Metagratings can achieve beam deflection by suppressing undesired diffraction effects with sparse arrangements of meta-atoms, enabling highly controlled and modulated electromagnetic wave propagation. However, most of the investigated metagratings are limited to applications in one single polarization. In this paper, we propose what we believe to be a new design of metagrating reflector with absorption and energy distribution properties along two orthogonal linear polarizations, respectively. To achieve the polarization-selective functionality aforementioned, the particle swarm optimization algorithm is introduced to calculate the optimal impedance density required, and the meta-atoms that can realize the calculated parameters along two polarization directions independently are exploited. Theoretical results show that the metagrating achieves a maximum absorption rate of 99.2% for x-polarization and an energy distribution ratio of diffraction orders is approximately set to 1:1:1 for y-polarization. A prototype is further fabricated and tested to validate the design, and it demonstrates good polarization-selective absorption/reflection as in the simulations. This work paves the path for various potential applications such as polarization beam splitters, covert communications, high-quality signal relaying, and electromagnetic compatibility.