Reversible decryption of covert nanometer-thick patterns in modular metamaterials

Bakan, Gökhan; Ayas, Sencer; Serhatlıoğlu, Murat; Dâna, Aykutlu; Elbüken, Çağlar

doi:10.1364/ol.44.004507

Cited by 8 publications

(8 citation statements)

References 29 publications

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“…Saturated and vivid colors can also be achieved by employing a Fabry–Pérot (FP) cavity, as shown in Figure g. − A Fabry–Pérot configuration is an optical cavity based on an interferometer or etalon that consists of two parallel reflective surfaces, first described and demonstrated by Fabry and Pérot back in 1899 . An FP cavity in its simplest design consists of a backreflector (made of metal or dielectric stack), and a dielectric with an optical thickness commensurate with multiples of half wavelengths of visible light in the cavity.…”

Section: Structural Color Generation Methods and Relevant Applicationsmentioning

confidence: 99%

Nanophotonic Structural Colors

et al. 2020

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Structural colors traditionally refer to colors arising from the interaction of light with structures with periodicities on the order of the wavelength. Recently, the definition has been broadened to include colors arising from individual resonators that can be subwavelength in dimension, e.g., plasmonic and dielectric nanoantennas. For instance, diverse metallic and dielectric nanostructure designs have been utilized to generate structural colors based on various physical phenomena, such as localized surface plasmon resonances (LSPRs), Mie resonances, thin-film Fabry-Pérot interference, and Rayleigh-Wood diffraction anomalies from 2D periodic lattices and photonic crystals. Here, we provide our perspective of the key application areas where structural colors really shine, and other areas where more work is needed. We review major classes of materials and structures employed to generate structural coloration and highlight the main physical resonances involved.

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Section: Structural Color Generation Methods and Relevant Applicationsmentioning

confidence: 99%

Nanophotonic Structural Colors

et al. 2020

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“…[ 30,31 ] Bakan et al. [ 32 ] reported a planar resonator‐type emitter that consists of an IR lossless dielectric layer sandwiched between a bottom metal reflector and a top lossy layer. Invisible patterns with strong thermal emission were obtained by patterning the ultrathin top layer that was transparent in the visible range but absorptive in the IR region.…”

Section: Introductionmentioning

confidence: 99%

Laser‐Printed Emissive Metasurface as an Anticounterfeiting Platform

Kim

Kang

et al. 2022

Laser & Photonics Reviews

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Optical security is a promising application of metasurfaces because light has large degrees of freedom in metasurfaces. Although many different structures/materials are proposed for this purpose, the fabrication of dynamic metasurfaces in a straightforward and scalable manner, while maintaining a high security level, remains a significant challenge. Herein, a metasurface consisting of a phase-changing GeSbTe layer and a metal back reflector is presented to space-selectively and dynamically control the infrared emission of the surface by a spatially modulated pulsed laser beam. Unlike conventional laser processes using a focused beam, the employed laser printing is an expanded beam-based parallel process that enables the fabrication of wafer-sized emission patterns. Owing to the multispectral responses of GeSbTe, mutually independent visible and infrared images can be printed in one region. Grayscale emission patterns can also be obtained by gradually modulating the spatial profile of the laser beam, which makes the replication of laser-printed emission patterns extremely difficult. These encouraging features indicate that the presented emissive metasurface has the potential for use as an effective platform for anticounterfeiting.

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“…In modern society, pirated goods have become a global issue as a source of illicit funds for crime organizations. [ 1 ] Some countermeasures such as physical anti‐counterfeiting technologies have been developed to prevent replication in various forms: watermarks, [ 2,3 ] intaglio printing, [ 4 ] luminescent ink, [ 5,6 ] thermal emissive label, [ 7–10 ] and magnetic ink. [ 11,12 ] Most importantly, thermal emissive labels using tailored infrared (IR) emissivity implemented using photonic structures have received significant research attention as a promising anti‐counterfeiting candidate owing to their facile design and fabrication process for a textured metal surface such as photonic crystal cavities, [ 13–16 ] nano‐antennas, [ 17–19 ] metamaterials, [ 20–22 ] and gratings.…”

Section: Introductionmentioning

confidence: 99%

Colored, Covert Infrared Display through Hybrid Planar‐Plasmonic Cavities

Lee

Kim

Yoo

et al. 2021

Advanced Optical Materials

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Artificial covert infrared (IR) displays have recently emerged as an anti‐counterfeiting method for spontaneous thermal emissive surfaces and optically encoded information. However, the unnatural appearance of a conventional thermal emissive label in the visible region limits the widespread application of an artificial covert IR display. This paper presents a colored, covert IR display exhibiting visible color patterns and thermally encoded data simultaneously based on a hybrid planar‐plasmonic cavity (HPPC). The HPPC is composed of two spectrally distinguished resonant structures: 1) an ultrathin planar cavity with an amorphous silicon (a‐Si) layer on gold (Au) for visible coloration and 2) an IR plasmonic cavity with hole‐patterned Au on a polymer substrate with a back mirror for thermal data encoding. Such hybridization of multi‐band resonance can not only enhance the vivid coloration but also enhance the data storage capacity per unit. Camouflage labels with encrypted thermal data are successfully demonstrated for practical applications using a flexible HPPC. Collectively, the proposed HPPC enables a new type of anti‐counterfeiting method that achieves both esthetic, visibly encoded data, and covert, thermally encoded data.

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Reversible decryption of covert nanometer-thick patterns in modular metamaterials

Cited by 8 publications

References 29 publications

Nanophotonic Structural Colors

Nanophotonic Structural Colors

Laser‐Printed Emissive Metasurface as an Anticounterfeiting Platform

Colored, Covert Infrared Display through Hybrid Planar‐Plasmonic Cavities

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