Gray Level Image Encoding in Plasmonic Metasurfaces
Gray Level Image Encoding in Plasmonic Metasurfaces
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DOI：
10.1007/s11468-020-01151-5
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发表时间：
2020-03
期刊：
影响因子：
3
通讯作者：
Ting Zhang;S. Blair
中科院分区：
文献类型：
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作者：
Ting Zhang;S. Blair
等离子体超颖表面已经广泛用于使用纳米级结构的图像和颜色表示。通过设计纳米结构的尺寸或形状，透射或反射的电磁光谱的相位或振幅可以经由控制共振波长来操纵，这导致多种颜色并且可以用于颜色和/或图像生成。代替彩色打印，我们引入了一种新的方法，可以生成具有多个灰度级的图像，并将其隐藏在特定波长的光下。在这项工作中，具有相同几何形状的纳米棒的等离子体结构在玻璃基板上以阵列形式制造，但纳米棒包含铝和钛的二元合金;因此，灰度图像信息用材料成分编码。在偏振沿着纳米棒的长轴的白色光照射下，纳米棒的响应具有基本上相同的谐振频率，但是具有不同的透射幅度。在此基础上，利用四种不同成分的纳米棒，实现了四种灰度级的成像。由于纳米棒对入射光的偏振和光谱组成敏感，在非偏振白色光照射下，图像消失。因此，该技术在图像加密中具有广阔的应用前景。我们还表明，通过这种方法在共振波长的光的操纵发生在振幅，而不是相位。
Plasmonic metasurfaces have been widely used for image and color representation using nanoscale structures. By designing the size or shape of nanostructures, the phase or amplitude of transmitted or reflected electromagnetic spectrum can be manipulated via control of resonant wavelength, which results in multiple colors and can be used for color and/or image generation. Instead of color printing, we introduce a new approach from which images with multiple gray scales can be generated and hidden under light with specific wavelengths. In this work, plasmonic structures of nanorods with identical geometries are fabricated in arrays on a glass substrate, but the nanorods comprise binary alloys of aluminum and titanium; therefore, grayscale image information is encoded with the material composition. Under white light illumination with polarization along the long axis of a nanorod, the response of the nanorods has essentially the same resonant frequency, but with varying magnitudes of transmission. Based on this, using nanorods with four different compositions, four gray level imaging has been achieved. Since nanorods are sensitive to the polarization and spectral composition of the incident light, under unpolarized white light illumination, the image disappears. Therefore, this technique is promising in image encryption. We also show that the manipulation of light at the resonant wavelength by this method occurs in amplitude, not phase.