Silicon multi‐meta‐holograms for the broadband visible light

Abstract

The dielectric metasurface hologram promises higher efficiencies due to lower absorption than its plasmonic counterpart. However, it has only been used, up to now, for controlling linear-polarization photons to form single-plane holographic images in the near-infrared region. Here, we report a transmissiontype metahologram achieving images in three colors, free from high-order diffraction and twin-image issues, with 8-level modulation of geometric phase by controlling photon spin via precisely patterned Si nanostructures with varying orientations. The resulting real and virtual holographic images with spin dependence of incident photons natively enable the spin degeneracy removal of light, leading to a metahologram-enabled spin Hall effect of light. Low-absorption dielectrics also enable us to create holograms for short-wavelength light down to 480 nm, thus spanning the three primary colors. It possesses the potential for compact color-display chips using mature semiconductor processes, and holds significant advantages over previous metaholograms operating at longer wavelengths.

Photon‐nanosieve for ultrabroadband and large‐angle‐of‐view holograms

“…It is worth noting that, although the modulation dispersion has been eliminated, the propagation kernel P describing the diffraction of a PS located at ( x n , y n ) provides the intrinsic propagation dispersion. This propagation dispersion cannot be eliminated in principle, however, it mainly influences the imaging position of a hologram and does not cause significant distortions or aberrations in the reconstructed holography image .…”

“…In contrast, geometric metasurfaces allow broadband operation for a circularly polarized light due to the dispersion‐less Pancharatnam–Berry phase . Unfortunately, their amplitude responses are closely related to the wavelength of plasmonic or magnetic resonance so that their efficiency decreases rapidly when the illuminating wavelength falls out of a narrow resonance band . To the best of our knowledge, the largest ever reported bandwidth of geometric metasurface holograms is ∼400 nm in both theory and experiment.…”

“…Recently, metasurfaces consisting of gradually varied nanostructures have been demonstrated in controlling phase and amplitude of a polarized light by plasmonic resonance in metals or magnetic resonance in dielectrics . These electromagnetic resonances are wavelength dependent, which determines that the phase or amplitude modulated by metasurfaces still has significant modulation dispersion (see Fig.…”

“…Furthermore, all these metasurface CGHs only work under either linear or circular polarization because the nanostructures respond selectively to the polarization of incident light . In addition, the absorption of high‐index dielectric materials makes them unsuitable for operation at shorter wavelengths such as the ultraviolet (UV) and blue ranges . There is no solution among existing holographic techniques to simultaneously enable polarization‐independent, distortion‐free, large angle‐of‐view and ultrabroadband operation spanning from the UV to near‐infrared (IR) wavelengths, which are highly desired for high‐performance holography.…”

Flat Helical Nanosieves

“…Examples include optical vortex plate, [6] ultrathin flat lens, [7][8][9][10] propagating wave to surface wave convertor, [11,12] broadband quarter-wave plate, [13] directional surface plasmon polaritons excitation, [14] and meta-hologram. [15][16][17][18][19][20] Especially for the Pancharatnam-Berry (PB) metasurface, [21] it transfers the interfacial phase distribution into orientations of base units, which largely simplifies the design process of optical antenna compared with those metasurfaces based on spatially varying geometric parameters (e.g., V-shaped metasurface, slot antenna array metasurface [22][23][24] ). Thus, metasurface provides new opportunities and strategies to develop ultrathin optical devices that are compatible with integrated and compact systems.…”