Multichannel vectorial holographic display and encryption

Abstract

Since its invention, holography has emerged as a powerful tool to fully reconstruct the wavefronts of light including all the fundamental properties (amplitude, phase, polarization, wave vector, and frequency). For exploring the full capability for information storage/display and enhancing the encryption security of metasurface holograms, smart multiplexing techniques together with suitable metasurface designs are highly demanded. Here, we integrate multiple polarization manipulation channels for various spatial phase profiles into a single birefringent vectorial hologram by completely avoiding unwanted cross-talk. Multiple independent target phase profiles with quantified phase relations that can process significantly different information in different polarization states are realized within a single metasurface. For our metasurface holograms, we demonstrate high fidelity, large efficiency, broadband operation, and a total of twelve polarization channels. Such multichannel polarization multiplexing can be used for dynamic vectorial holographic display and can provide triple protection for optical security. The concept is appealing for applications of arbitrary spin to angular momentum conversion and various phase modulation/beam shaping elements.

Complete Control of Multichannel, Angle‐Multiplexed, and Arbitrary Spatially Varying Polarization Fields

“…This means that one can use coherent pixel polarization metaholography to generate arbitrary spatially varying polarization beams, including a full Poincaré beam and vectorial images . Additionally, for the noncircular case of | e + 〉 ≠ | R 〉 or | L 〉, such as in arbitrary spin to orbital conversion and a polarization‐multiplexed display, from Equation , one can see that the polarization pairs of |( e i ) ϑ 〉 or maintain orthogonality for a linearly polarized incident illumination. This is because 〈( e + ) ϑ |( e − ) ϑ 〉 = 0 and for an arbitrary value of ϑ.…”

“…Interestingly, the spin‐controllable character can be maintained when using the circular polarization basis. It should be noted that such an ultrathin multifunctional metasurface can be fabricated by standard complementary metal‐oxide semiconductor processes, and will enable a broad range of applications, such as optical polarization Möbius strips, polarization‐encrypted data, and quantum experiments, a fiber mode‐multiplexed communication system and arbitrary polarization‐multiplexed print images …”

“…The utilization of a vectorial optical field with complete control over the phase, amplitude, and polarization has recently become a topic of extensive interest . In particular, vectorial optical fields with an arbitrary spatially varying polarization distribution are playing an increasingly important role in the scientific discoveries of many physical systems and a variety of applications, ranging from optical encryption to communication . For example, vector beams have been considered to be a promising candidate for an optical mode‐division multiplexing system, optical storage, and quantum key distribution .…”

“…Full Poincaré beams have been used to investigate physical systems with exotic nonlinear dynamics . The applications of optical images with spatially varying polarization manipulation include dynamic displays and information encryption . An attempt has also been made to reconstruct a Seifert surface structure by analyzing the polarization ellipse orientations of knotted polarization singularities …”

Quantitatively Correlated Amplitude Holography Based on Photon Sieves

“…[7] Meanwhile, conventional CGHs based on spatial light modulators (SLM) inevitably generate reconstruction images with limited resolution and low field-of-view (FOV) because of large pixel size compared with wavelength. Abrupt phase discontinuities can be generated within ultrashort distance, and different phase modulation methods by means of resonance phase [15][16][17][18][19] or Pancharatnam-Berry (PB) phase [7,17,[19][20][21] have been revealed. [9][10][11][12][13][14] In previously reported works, phase-only metasurface holograms are employed most widely due to the excellent wavefront modulation properties.…”