Single-sized multifunctional metasurfaces for simultaneous nanoprinting and holography inspired by tri-redundancy

Polarization-encoded optical secret sharing based on a dielectric metasurface incorporating near-field nanoprinting and far-field holography

Metasurface encryption with high concealment and resolution is promising for information security. To improve the encryption security, a polarization-encoded secret sharing scheme based on dielectric metasurface by combining the secret sharing method with nanoprinting and holography is proposed. In this encryption scheme, the secret image is split into camouflaged holograms of different polarization channels and shares a total of 24-1 encryption channels. Benefiting from the secret sharing mechanism, the secret image cannot be obtained by decoding the hologram with a single shared key. Specifically, the secret hologram of a specific channel in the far field can be obtained by specifying the optical key, acquiring the near-field nanoprinting image to determine the combination order for the shared key, and decoding using multiple shared keys. The secret sharing encryption scheme can not only enhance the security level of metasurface encryption, but also increase the number of information channels by predefining camouflage information. We believe that it has important potential applications in large-capacity optical encryption and information storage.

Phase-assisted Bessel-metasurface: a single-sized approach for simultaneous printing and holography

Due to the unprecedented wavefront shaping capability, the metasurface has demonstrated state-of-the-art performances in various applications, especially in printing and holography. Recently, these two functions have been combined into a single metasurface chip to achieve a capability expansion. Despite the progress, current dual-mode metasurfaces are realized at the expense of an increase in the difficulty of the fabrication, reduction of the pixel resolution, or strict limitation in the illumination conditions. Inspired by the Jacobi-Anger expansion, a phase-assisted paradigm, called Bessel metasurface, has been proposed for simultaneous printing and holography. By elaborately arranging the orientations of the single-sized nanostructures with geometric phase modulation, the Bessel metasurface can not only encode a greyscale printing image in real space but can reconstruct a holographic image in k-space. With the merits of compactness, easy fabrication, convenient observation, and liberation of the illumination conditions, the design paradigm of the Bessel metasurface would have promising prospects in practical applications, including optical information storage, 3D stereoscopic displays, multifunctional optical devices, etc.

Phase-assisted angular-multiplexing nanoprinting based on the Jacobi-Anger expansion

Featuring with ultracompactness and subwavelength resolution, metasurface-assisted nanoprinting has been widely researched as an optical device for image display. It also provides a platform for information multiplexing, and a series of multiplexed works based on incident polarizations, operating wavelengths and observation angles have emerged. However, the angular-multiplexing nanoprinting is realized at the cost of image resolution reduction or the increase of fabrication difficulty, hindering its practical applications. Here, inspired by the Jacobi-Anger expansion, a phase-assisted design paradigm, called Bessel metasurface, was proposed for angular multiplexing nanoprinting. By elaborately designing the phase distribution of the Bessel metasurface, the target images can be encoded into the desired observation angles, reaching angular multiplexing. With the merits of ultracompactness and easy fabrication, we believe that our design strategy would be attractive in the real-world applications, including optical information storage, encryption/concealment, multifunctional switchable optical devices, and 3D stereoscopic displays, etc.