Efficient dielectric metasurface hologram for visual-cryptographic image hiding

Li, Zhenfei; Dong, Guoyan; Yang, Dongyu; Li, Guilin; Shi, Yishi; Bi, Ke; Zhou, Ji

doi:10.1364/oe.27.019212

Cited by 35 publications

(21 citation statements)

References 22 publications

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“…Nanopost meta‐atoms (NPMs) can be components of meta‐holograms 71 . NPMs can modulate a phase of the propagating light depending on the size of diameters 72–82 .…”

Section: Effects Of Meta‐atom On Hologram Characteristicsmentioning

confidence: 99%

Geometric and physical configurations of meta‐atoms for advanced metasurface holography

Kim

Yang

Badloe

et al. 2021

InfoMat

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Metasurfaces consisting of subwavelength structures, so‐called meta‐atoms, have steadily attracted considerable attention for advanced holography due to their advantages in terms of high‐resolution holographic images, large field of view, and compact device volume. In contrast to conventional holographic displays using bulky conventional diffractive optical elements, metasurface holography enables arbitrary complex wavefront shaping with a much smaller footprint. In this review, we classify metasurface holography according to the meta‐atom design methodologies, which can further expand hologram functionalities. We describe light‐matter interactions, particularly in metasurface systems, using the relevant the Jones matrix to rigorously explain modulations of the amplitude, phase, and polarization of light. Six different types of meta‐atoms are presented, and the corresponding achievable wavefronts that form the holographic images in the far‐field are also provided. Such a simple classification will give a straightforward approach to design and further realize advanced metasurface holographic devices.

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“…Nanopost meta‐atoms (NPMs) can be components of meta‐holograms 71 . NPMs can modulate a phase of the propagating light depending on the size of diameters 72–82 .…”

Section: Effects Of Meta‐atom On Hologram Characteristicsmentioning

confidence: 99%

Geometric and physical configurations of meta‐atoms for advanced metasurface holography

Kim

Yang

Badloe

et al. 2021

InfoMat

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“…Since visual cryptography (VC) was developed (Naor and Shamir, 1995), there are many relevant studies for its applications. The VC offers a feasible and straightforward solution for the decryption of secret information based on human vision (Naor and Shamir, 1995;Blundo et al, 2000;Hou, 2003;Wan et al, 2018;Yang et al, 2018;Jiao et al, 2019;Li et al, 2019;Jiao et al, 2020). The first visual cryptographic technique was proposed by Naor and Shamir in 1995, which broke up a secret image into multiple shares (i.e., visual key images) (Naor and Shamir, 1995).…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, visual key images can be further designed using quick response patterns or phase holograms (Wan et al, 2018;Jiao et al, 2020). The visual key images are printed onto holographic optical elements (HOEs) or metasurface, and then the secret images can be visually decoded when these visual key images are overlapped (Yang et al, 2018;Li et al, 2019). Although VC scheme provides an effective way to realize encryption by using pixel expansion rule and decode the secret information based on human vision, conventional VC techniques could have some disadvantages.…”

Section: Introductionmentioning

confidence: 99%

Visual Cryptography Using Binary Amplitude-Only Holograms

et al. 2022

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Visual cryptography (VC) is developed to be a promising approach to encoding secret information using pixel expansion rules. The useful information can be directly rendered based on human vision without the usage of decryption algorithms. However, many VC schemes cannot withstand occlusion attacks. In this paper, a new VC scheme is proposed using binary amplitude-only holograms (AOHs) generated by a modified Gerchberg-Saxton algorithm (MGSA). During the encryption, a secret image is divided into a group of unrecognizable and mutually-unrelated shares, and then the generated shares are further converted to binary AOHs using the MGSA. During image extraction, binary AOHs are logically superimposed to form a stacked hologram, and then the secret image can be extracted from the stacked hologram. Different from conventional VC schemes, the proposed VC scheme converts a secret image into binary AOHs. Due to the redundancy of the generated binary AOHs, the proposed method is numerically and experimentally verified to be feasible and effective, and possesses high robustness against occlusion attacks.

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“…Zhao et al implemented the rod slot antennas and C-shaped slot antennas are used as building blocks to achieve multi-image hiding and seeking with polarization control in the terahertz band in 2019 [22]. Li et al hided the encrypted images in two metasurfaces respectively, and superimposed the reconstructed holograms by optical method to realize the reproduction of the target image [23]. Both of the methods use static metasurfaces for achieving hidden encryption of information, thus we would like to extend metasurfaces to a tunable one for information encryption and hiding, which can enhance the diversity of information hiding methods and greatly enhance the security level of information [24].…”

Section: Introductionmentioning

confidence: 99%

Electrically Tunable All-Dielectric Metasurfaces Integrated With Nematic Liquid Crystals for Information Encryption

Shen

Sun

et al. 2021

IEEE Photonics J.

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As artificially designed two-dimensional (2D) arrays of subwavelength nanostructures, metasurfaces provide a new avenue for the design of static planar optics. However, one would prefer a dynamic modulation of the metasurface in the event of practical applications. As a potentially important technique for information security, meta-holographic encryption has the characteristics of subwavelength pixels, precise control, and high safety factor. In this paper, by integrating birefringent liquid crystals (LCs) with all-dielectric metasurfaces in combination with visual cryptography (VC), we demonstrate a tunable metasurface with an information encryption function in the visible range. In the encryption process, the secret image is hidden in a set of unidentifiable and orthogonal arranged phase-only meta-holograms with high security of concealment. In the decryption process, the generated meta-hologram is illuminated by a plane wave and an electric field across the LC layer is applied to superimpose the reconstructed holographic patterns, thus we could acquire the secret image. Therefore, the decryption method can be flexibly and sufficiently adjusted with applied field under monitorable condition. For this reason, it is useful in enhancing the diversity of information hiding methods and improving the security of information. Our method can be extended to other similar applications.

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Efficient dielectric metasurface hologram for visual-cryptographic image hiding

Cited by 35 publications

References 22 publications

Geometric and physical configurations of meta‐atoms for advanced metasurface holography

Geometric and physical configurations of meta‐atoms for advanced metasurface holography

Visual Cryptography Using Binary Amplitude-Only Holograms

Electrically Tunable All-Dielectric Metasurfaces Integrated With Nematic Liquid Crystals for Information Encryption

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