Large-format optical encryption device of vector light field based on pixelated metagratings

In this paper, we propose a novel optical encryption scheme of vector light field based on the large-format metagrating device. The pixelated metagratings are utilized as vector light field modulation units to modulate the phase of incident light pixel by pixel, so as to precisely manipulate the propagation directions of directional vector light beams and accurately project them to specific positions in image space. In combination with the ciphertext amplitude information provided by image masks, the optical target images are eventually reconstructed on a given imaging plane. We experimentally fabricate large-format metagrating array elements (90 mm×90 mm) and satisfactorily accomplish the tasks of image encryption encoding and optical decoding, capturing the reconstructed images with fine visual quality. Metagrating elements are simple to design and can be easily fabricated on a large scale with low cost, contributing to the promotion and practical applications of optical encryption technology.