Optical encryption in spatial frequencies of light fields with metasurfaces

Abstract

Optical encryption has attracted attention recently as information security becomes important in modern society. For most encryption methods based on metasurfaces, however, information is encrypted into the metasurfaces of physical forms, limiting information sharing and compatibility with digital information processing technology. Here, we demonstrate an alternative scheme in which information is encrypted on optical images other than metasurfaces, releasing the constraints mentioned above. This is achieved by modulating the spatial frequencies of optical images with metasurfaces. Specifically, information encryption and decryption based on the intensity or phase of spatial frequency have been demonstrated with the developed microscopic Fourier optics technique. The abundance of spatial frequency also promises a flexible multiplexing platform for increasing information capacity, which has been verified by a 4-bit encryption experiment. These findings could enable high-security and high-capacity optical encryption platforms.

Research on multiple-image encryption method using modified Gerchberg–Saxton algorithm and chaotic systems

“…7(6)-7 (8) show the R, G, and B channels of the encrypted ciphertext, all with size 600 × 600; and Figs. 7(9)-7 (12) show the decrypted reconstructed images. The decryption reconstruction performance is illustrated in Table 1.…”

“…8, Figs. 8(1)-8 (12) show plaintexts; Fig. 8 (13) shows the encrypted ciphertext with size 600 × 600 × 3; Figs.…”

“…Additionally, multiple-image encryption has received more attention compared with single-image encryption as it improves encryption capabilities and makes it easier to transmit and store multiple images. Although double random phase encryption 6 (DRPE) pioneered the application of optical principles to image encryption in 1995, due to the high capacity, high concurrency, and multiple dimensions of the optical system, optics began to be closely combined with other methods to develop a wide variety of encryption algorithms 7 that are widely used in image information security, such as interference encryption, 8 joint transform correlator encryption, 9 digital holography encryption, 10 metasurface encryption, 11 , 12 ghost imaging encryption, 13 ptychography encryption, 14 etc.…”

Inkjet Printing of Biocompatible Luminescent Organic Crystals for Optical Encryption

“…The rapid growth of the consumer market raises a problem for protecting personal information and goods from counterfeiting, thus forming a new direction in material science and digital technology to encrypt the information. − One of the promising solutions, combining new materials and encryption technologies, is optical information encryption, since it is a quite fast, remote, safe (including for human health), and low-energy-consumptive approach. − In most cases, optically active or photoluminescent inorganic, organic, and hybrid materials − are utilized for optical encryption through a change in their color or photoluminescent (PL) signal. However, the design and fabrication of the optical security marks on arbitrary surfaces with PL decoding, allowing also a human contact, is still in its infancy.…”

Optical Steganography via Programmable Anchoring Boundary of Soft Materials

“…[17,18] For example, by exploiting the orientation degeneracy approach, Malus's law-assisted metasurface is able to record independent images into a shared aperture without crosstalk, and the image information can be readily retrieved with polarizers. [19] In addition, some researches have proposed that a target information is able to be hidden in camouflaged image, [9] laser beam, [20] and even spatial frequencies of light fields, [21] further inspiring novel anti-counterfeiting technology with a high level of security. However, the sophisticated fabrication, wavelength-dependent efficiency, and limited size are the main obstacles in practical applications.…”