Bidirectional Augmented Reality 3D Signage Enabled by a Metagrating Waveguide

In this article, we proposed a see-through three-dimensional (3D) signage system that can be observed on both sides. It comprises two parts: a light emitting diode light source and an edge-lit waveguide embossed with pixelated metagratings. Two sets of sparsely distributed metagrating matrices were carefully designed to reconstruct a dual-color 3D virtual scene while maintaining high transparency. The transparency of the waveguide was above 70%, and the complex wavelet structural similarity value was 0.93, suggesting a high image fidelity for objects seen through the waveguide. 3D virtual images with correct motion parallax were obtained at both the front view and back view. The viewing angle of the 3D signage was 60°. The proposed augmented reality 3D signage features high transparency, bicolor, wide viewing angle with nonrepeating views, and thin format. Potential applications include window displays, colored signage, and advertisements.