Figure 5.
Information encryption meta‐hologram. a) The top secret content to be sent, which is a word “Message.” b) Compiling method of the word “Message” to 6‐digit binary codes using the s 1, s 2, and s 3 of the selected eight polarization states. Each code is composed by the s 1, s 2, and s 3 values of two adjacent spots. c) Tilted SEM image of part of the fabricated meta‐hologram. Scale bar: 300 µm. d) Measured image in the Ψ channel for providing the key information of reading sequence. e–g) Measured images in the s 1, s 2, and s 3 channels after taking step function operations for providing the encrypted coding information. h) Measured image in the s 0 channel for providing the key information of the cipher book number. i) Extracted 75 bits of binary codes from (e–g) based on the reading sequence guided by (d). j) Decoded secret information from (i) using the cipher book indexed by (h). The results are all measured at 1.05 THz under x‐polarized incidence.