Metasurface-based key for computational imaging encryption

Abstract

Optical metasurfaces can offer high-quality multichannel displays by modulating different degrees of freedom of light, demonstrating great potential in the next generation of optical encryption and anti-counterfeiting. Different from the direct imaging modality of metasurfaces, single-pixel imaging (SPI) as a typical computational imaging technique obtains the object image from a decryption-like computational process. Here, we propose an optical encryption scheme by introducing metasurface-images (meta-images) into the encoding and decoding processes as the keys of SPI encryption. Different high-quality meta-images generated by a dual-channel Malus metasurface play the role of keys to encode multiple target images and retrieve them following the principle of SPI. Our work eliminates the conventional digital transmission process of keys in SPI encryption, enables the reusability of a single metasurface in different encryption processes, and thereby paves the way toward a high-security optical encryption between direct and indirect imaging methods.

Tunable metasurfaces towards versatile metalenses and metaholograms: a review

“…A single metasurface can produce tunable hologram images by controlling the properties of incident light sources that enter the metasurfaces. In this section, we discuss tunable metahologram research that considers regulating the polarization state, [128][129][130][131][132][133][134][135] orbital angular momentum (OAM), 54,[136][137][138][139] and coding incident beam. 67,[140][141][142] Above these, other methods include modulating the wavelength or angle of the incident beam, which have also been used to realize tunable holographic images.…”

“…A proposed new encryption process uses different metaholograms as the keys of imaging encryption. 135 The process uses dual-channel Malus metasurfaces to exploit high-quality images, which can generate a matrix during the encoding and decoding processes. Different channels of the metasurface can contain different matrix information to increase the number of keys available to encryption or anti-counterfeiting systems.…”

Generalized multi-channel scheme for secure image encryption

“…This capability suggests intriguing new possibilities for spatial and spectral encryption. For example, metasurfaces have been used to visually “hide” an image by distributing its pixels over multiple wavelength 31 – 33 or polarization 24 channels. In this work, the original image was easily recovered by summing over channel outputs.…”

Metasurface-enabled three-in-one nanoprints by multifunctional manipulations of light

“…By judiciously designing the geometry and orientation of each nanostructure, metasurfaces have been employed to act as optical functional elements such as metalenses ( Wang et al., 2018 ; Wang et al., 2021 ; Li et al., 2021a ; Chen et al., 2018a ; Zheng et al., 2017 ; Fu et al., 2019 ), meta-holograms ( Li et al., 2017 ; Jiang et al., 2019 ; Li et al., 2020a ; Li et al., 2020b ; Fu et al., 2020 ; Hu et al., 2019 ; Deng et al., 2020a ; Zhang et al., 2020 ; Kim et al., 2021a ; Ren et al., 2020 ), meta-gratings ( Yang et al., 2021 ; Li et al., 2018 ; Fang et al., 2020 ; Li et al., 2015a ), vortex beam generators ( Hu et al., 2021 ; Chen et al., 2018b ; Dai et al., 2020a ; Guo et al., 2016 ), and quantum information carriers ( Solntsev et al., 2021 ; Zhu et al., 2020 ; Li et al., 2020c ). Among them, metasurface-based nanoprints have attracted extensive interest due to their subwavelength resolution, durable properties, nonfading colors, and zero-pollution ( Chen et al., 2019a ; Yang et al., 2020 ; Zheng et al., 2021 ; Kim et al., 2021b ; Chen et al., 2019b ; Jung et al., 2020 ). Benefiting from the spectral tunability of metasurfaces, various approaches have been proposed to encode nanoprinting images with different colors onto a single metasurface.…”