Cao Yue, Tang Lili, Li Jiaqi, Wang Jin, Dong Zheng-Gao
Opt Lett. 2020 Sep 15;45(18):5181-5184. doi: 10.1364/OL.403229.
It is important to arbitrarily manipulate optical intensity, an important degree of freedom to light, on microscales, which is a fundamental requirement for integration and miniaturization of optical devices. Metasurfaces have shown unprecedented capabilities for manipulating light in terms of phase, intensity, and polarization. Here, an ultrathin metasurface composed of silver nanorods illuminated by linearly polarized light is demonstrated to manipulate optical intensity in subwavelength scales. By modulating rod orientations, gradient reflectance of light can be achieved on dual-wavelength regimes with contrast reflection intensities. Further, a nanorod metasurface, embedded with a picture of a panda profile, is experimentally designed for grayscale imaging, and the measurements demonstrate that two complementary grayscale images can be displayed at 633 and 900 nm. The grayscale imaging by a proposed ultrathin metasurface with dual-wavelength, complementary, and subwavelength-resolution characteristics provides a simple but efficient way for tailoring optical intensity on subwavelength scales, which is promising for a variety of applications such as encryption and decryption, display, information security, and optical communication.
在微尺度上任意操纵光强（光的一个重要自由度）非常重要，这是光学器件集成和小型化的基本要求。超表面在相位、强度和偏振方面展现出了前所未有的光操纵能力。在此，展示了一种由线性偏振光照射的银纳米棒组成的超薄超表面，可在亚波长尺度上操纵光强。通过调制棒的取向，可在具有对比反射强度的双波长 regime 上实现光的梯度反射率。此外，实验设计了一种嵌入熊猫轮廓图片的纳米棒超表面用于灰度成像，测量结果表明在 633 和 900 nm 处可显示两个互补的灰度图像。所提出的具有双波长、互补和亚波长分辨率特性的超薄超表面进行灰度成像，为在亚波长尺度上定制光强提供了一种简单而有效的方法，这在诸如加密和解密、显示、信息安全和光通信等各种应用中具有广阔前景。
