High‐Performance Transmission Structural Colors Generated by Hybrid Metal‐Dielectric Metasurfaces

Abstract

our previous work, the wide static colors exceeding 170% sRGB (standard RGB) space can be obtained by utilizing index matching among trilaminar dielectric nanoblocks to deeply modulate multipolar modes of reflection resonance. [19] Carrillo et al. proposed switchable phasechange metasurface resonant absorber to selectively absorb colors in the crystalline phase, providing potential development in front-end color displays, and color electronic signage. [23] For the structural colors in transmission mode, the majority of previous studies mainly focused CMYK color model since all-dielectric nanostructures can readily generate high-monochromaticity transmission valley. [10,[17][18][19][25][26][27][28][29] Realizing of highperformance transmission colors in RGB color model remains a challenge. Table 1 presents several representative designs to realize transmission colors in RGB model. [30][31][32][33][34][35][36][37][38] In the infancy, the strategy of arrayed nanoholes or nanoslits in optically-thick metallic films was extensively used to provide surface-plasmon enhanced transmission. [20][21][22][23][24][25][26][27][28][29][30][31][32] But only broad spectra with low efficiency and monochromaticity can be obtained because metallic materials hold high ohmic loss. In order to improve the quality of transmission spectra, the designs of metal-dielectric hybrid nanostructures were applied to realize structural colors with higher saturation. [33][34][35][36][37][38] For instance, Yun et al. proposed a bilayer hybrid metasurface consisting of Al nanogratings and asymmetrical amorphous Si nanorods. [35] Although the cavity effects between bi-matasurfaces can lead to unprecedented high-saturation colors taking up 90% sRGB space in the simulation, the low efficiency of about 16% and complicated Despite structural colors based on metasurfaces drawing enormous attentions due to the high resolutions and superior durability, few researches focus on transmission colors in RGB model with high saturation because high-monochromaticity transmission peak is hard to be realized. Herein, a strategy of high-performance transmission structural colors in RGB model with high saturation, full hue, high efficiency, easy manufacturability, and polarization independence by means of Al-Si 3 N 4 nanoblocks deposited on glass substrate is proposed. The coupling between Wood's anomaly and Mie lattice resonance is capable of introducing magnetic-dipole and electricquadrupole resonances, creating enhanced resonant peak with full width of half maximum (FWHM) of 50 nm and efficiency of over 70% in transmission mode. High-saturation transmission colors occupying 150% standard RGB (sRGB) space can be obtained for the first time by tailoring the geometric parameters. Besides, it is also demonstrated that the hybrid nanostructures can realize full-hue colors with constant resolutions, which is significant for imaging applications. The designed method has potential for further extending the applications of transmission colors.

Deep Subwavelength Wide‐Angle Structural Colors at the Single Pixel Level

“…[31] The spatial resolution will be restricted although the lattice effects can expand the color space. [40][41][42] Therefore, the chiral metasurface may be a new idea to control spectrum at the single pixel level since a single chiral nanounit can tailor the spectrum by polarization. [77] The optical bright field microscope images in Figure 3e also demonstrate that the nanodisks with different diameters exhibit distinct vivid colors such as cyan, magenta, yellow (CMY), showing the ability to generate colors based on the gap-plasmon cavity mode.…”

“…As in photonic crystals, metasurfaces require repeated in-plane unit cells despite the subwavelength thickness, which leads to noncompact pixels and strong angular sensitivity in their optical responses. [40][41][42] Similar obstacles exist for structures consisting of individual nanoparticles. High-index dielectric nanoparticles suffer from the larger modal volume of Mie resonances since the wavelength of the lowest frequency magnetic dipole resonance of a dielectric nanosphere relates to the diameter d by λ MD = nd where n is the refractive index of dielectrics.…”

Advances in Meta-Optics and Metasurfaces: Fundamentals and Applications

“…Previous efforts often focused on metallic metasurfaces [ 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 ], which can enhance light–matter interactions and introduce versatile control of incoming light by activating local plasmonic resonance, albeit with limited efficiency due to ohmic loss [ 78 , 79 , 80 , 81 , 82 , 83 ]. Dielectric metasurfaces overcome the limitation of metallic metasurfaces, which have provided a promising way to develop highly efficient and multi-functional meta-devices [ 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 ].…”

Compressive Imaging Encryption with Secret Sharing Metasurfaces

“…[ 19–26 ] Metasurfaces, consisting of single‐layer or fewer‐layer spatially variant meta‐units, enable unprecedented control over the phase profile and other degrees of freedom of light with subwavelength resolution. [ 27–42 ] With polarization or wavelength control, optical metasurface holography has been exploited to convert visible object images into unrecognizable phase‐only distributions, providing an effective way to imprint secret information. [ 43–50 ] With judiciously engineered polarization responses of incident and outgoing beams, multiple‐channel Malus metasurfaces have found potential applications in both optical anti‐counterfeiting and encryption.…”

“…[19][20][21][22][23][24][25][26] Metasurfaces, consisting of single-layer or fewer-layer spatially variant meta-units, enable unprecedented control over the phase profile and other degrees of freedom of light with subwavelength resolution. [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] With polarization or wavelength control, optical Exploiting various degrees of freedom of light, metasurfaces have unique advantages in multiple-channel information storage and demonstration, which thereby provides a novel platform to convey the keys and cipher images for different encryptions. Following the secret sharing principle of visual cryptography (VC), the authors here successfully embed both the keys and cipher images of computational ghost imaging (CGI) encryption into the holographic metasurface-images (meta-images).…”