Fig. 4From: High-dimensional Poincaré beams generated through cascaded metasurfaces for high-security optical encryptionOptical encryption demonstration based on cascaded metasurfaces. a The optical microscope images of two arrayed metasurfaces both including 16 × 10 cells which serve as ciphertext. Scale bar: 200 μm. b Information decryption by generating HDPBs through alignment of two metasurfaces according to the customized keys in the form of coordinates (x1, y1, x2, y2) for four users (each user possesses two keys). c The obtained messages about five parameters of the generated HDPBs and (d) the corresponding retrieved 4-bit Unicode characters based on look-up table. e The decrypted plaintext of four Chinese characters through Unicode encoding by four usersBack to article page