Li Yun Bo, Li Lian Lin, Xu Bai Bing, Wu Wei, Wu Rui Yuan, Wan Xiang, Cheng Qiang, Cui Tie Jun
State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China.
Department of Electronics Engineering and Computer Science, Peking University, Beijing, 100871, China.
Sci Rep. 2016 Mar 30;6:23731. doi: 10.1038/srep23731.
The programmable and digital metamaterials or metasurfaces presented recently have huge potentials in designing real-time-controlled electromagnetic devices. Here, we propose the first transmission-type 2-bit programmable coding metasurface for single-sensor and single- frequency imaging in the microwave frequency. Compared with the existing single-sensor imagers composed of active spatial modulators with their units controlled independently, we introduce randomly programmable metasurface to transform the masks of modulators, in which their rows and columns are controlled simultaneously so that the complexity and cost of the imaging system can be reduced drastically. Different from the single-sensor approach using the frequency agility, the proposed imaging system makes use of variable modulators under single frequency, which can avoid the object dispersion. In order to realize the transmission-type 2-bit programmable metasurface, we propose a two-layer binary coding unit, which is convenient for changing the voltages in rows and columns to switch the diodes in the top and bottom layers, respectively. In our imaging measurements, we generate the random codes by computer to achieve different transmission patterns, which can support enough multiple modes to solve the inverse-scattering problem in the single-sensor imaging. Simple experimental results are presented in the microwave frequency, validating our new single-sensor and single-frequency imaging system.
近期出现的可编程数字超材料或超表面在设计实时控制电磁设备方面具有巨大潜力。在此，我们提出了首个用于微波频段单传感器单频成像的透射型2位可编程编码超表面。与现有的由有源空间调制器组成且其单元独立控制的单传感器成像器相比，我们引入随机可编程超表面来变换调制器的掩膜，其中其行和列同时受到控制，从而可大幅降低成像系统的复杂度和成本。与采用频率捷变的单传感器方法不同，所提出的成像系统在单频下使用可变调制器，这可避免目标色散。为实现透射型2位可编程超表面，我们提出了一种双层二进制编码单元，便于分别改变行和列的电压来切换顶层和底层的二极管。在我们的成像测量中，我们通过计算机生成随机码以实现不同的传输模式，这可支持足够多的模式来解决单传感器成像中的逆散射问题。在微波频段给出了简单的实验结果，验证了我们新的单传感器单频成像系统。
