Wide gamut, angle-insensitive structural colors based on deep-subwavelength bilayer media

Abstract

<jats:title>Abstract</jats:title><jats:p>Wide gamut and angle-insensitive structural colors are highly desirable for many applications. Herein, a new type of lithography-free, planar bilayer nanostructures for generating structural colors is presented, which is basically composed of a deep-subwavelength, highly absorbing dielectric layer on an opaque metallic substrate. Experimental results show that a galaxy of brilliant structural colors can be generated by our structures, and which can cover ∼50% of the standard red–green–blue color space by adjusting the nanostructure dimensions. The color appearances are robust with respect to the angle of vision. Theoretical partial reflected wave analyses reveal that the structural color effect is attributed to the strong optical asymmetric Fabry–Perot-type (F–P-type) thin-film resonance interference. The versatility of the structural color properties as well as the simplicity of their fabrication processes make this bilayer structures very promising for various applications, such as security marking, information encryption, and color display, etc.</jats:p>

Near-zero reflection of all-dielectric structural coloration enabling polarization-sensitive optical encryption with enhanced switchability

“…Geometrical studies about d and P have been conducted to investigate the reflectance spectrum. Although the results have a narrower viewing angle (Supplementary Note 4) than other structural color devices [44,45], the performance which is displayed with the CIE and HSV color diagrams shows these color filter designs significantly reduce residual colors when turned-off. As a validation of the completely switchable encryption, practical applications of QR code encryption, two-color image switching, and overlapped images resolving are demonstrated.…”

Large area patterning of ultra-high thermal-stable structural colors in transparent solids

“…Fixing the diffraction order and detecting angle, λ of the band linearly increases with d, and the k 1 is determined to be 1.71. To directly illustrate the rich colors achieved from our structures, each spectrum is converted into the RGB color value [1][2][3][19][20][21][22][23] . The Commission on Illumination (CIE) 1931 chromaticity coordinates corresponding to the generated colors with diverse grating periods are illustrated in Fig.…”

“…Structural colors have attracted conspicuous interest due to their fascinating potential in the applications of sensors, optical data storage, information encryption, and display devices. Now, vivid structural colors can be generated through the interaction of light with periodic structures-most of their period (d) is comparable to the light wavelength [1][2][3] . Although as frequently suggested that the structural colored materials show superior stability compared with the colored chemical dyes and pigments, their stability at high temperature (e.g., > 700°C) is intrinsically poor due to the large surface area of the sub-micrometer structures.…”

Ta/NiO subwavelength bilayer for wide gamut, strong interference structural color

“…The underlying mechanism for the creation of various colors can be explained in terms of multiple light reflections that occur at the film surface (here NiO) and the interface between the film and the non-perfect metallic substrate (here Ta) as sketched in figure 3(a) [15,45]. Complex refractive indices of the film and metallic substrate results in non trivial interface phase shifts , which can be modified by varying the degree of loss in the film and substrate [13,15,16,46,47].…”