Abstract
Abstract Structural coloration using metasurfaces has been steadily researched to overcome the limitations of conventional color printing using pigments by improving the resolution, lowering the toxicity, and increasing the durability. Many metasurfaces have been demonstrated for dynamic structural coloration to convert images at the visible spectrum. However, the previous works cannot reach near-zero scattering when colors are turned-off, preventing it from being cryptographic applications. Herein, we propose a completely on/off switchable structural coloration with polarization-sensitive metasurfaces, enabling full-colored images to be displayed and hidden through the control of the polarization of incident light. It is confirmed that the nanostructure exhibits the polarization-dependent magnetic field distributions, and near-zero scattering is realized when the polarization of incident light is perpendicular to the long axis of the nanofins. Also, the metasurfaces are made up of triple-nanofin structures whose lengths affect locations of resonance peaks, resulting in full-color spectrum coverages. With such advantages, a QR code image, a two-color object image, and an overlapped dual-portrait image are obtained with the metasurfaces. Such demonstrations will provide potential applications in the fields of high-security information encryption, security tag, multichannel imaging, and dynamic displays.
Highlights
Structural coloration, the generation of colors through the use of micro- or nanostructures, has been steadily studied due to advantages such as long-term durability, high resolution, and lower toxicity compared to conventional pigment-based colorations [1,2,3,4]
Phenomena that arise from light–matter interactions such as localized surface plasmon resonances (LSPRs) [10,11,12,13] and Mie-resonances [14, 15] allow for the production of structural colors from metasurfaces
The nanofins are composed of hydrogenated amorphous silicon (a-Si:H) that exhibits a high refractive index in the visible range
Summary
Structural coloration, the generation of colors through the use of micro- or nanostructures, has been steadily studied due to advantages such as long-term durability, high resolution, and lower toxicity compared to conventional pigment-based colorations [1,2,3,4]. Some efforts using phase change materials to change structural colors on metasurfaces have been made, performances of color switching and active control are not enough for practical usages [36,37,38] In this sense, metasurfaces that produce full structural colors in the “on” state and near-zero reflectance in the “off” state have been rarely reported. The experimentally fabricated and measured metasurfaces confirm the capability of producing red, green, and blue colors that switch off to black when the polarization of the incident light is changed. This is confirmed through the HSV color space as the brightness of the colors drops to almost zero. These triple-nanofin metasurfaces (TNMs) could be used for applications such as ultrahigh-resolution images, full-color displays, optical storage media, security tags, and encryption technologies
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