Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, USA.
Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands.
Phys Rev Lett. 2018 Oct 26;121(17):173004. doi: 10.1103/PhysRevLett.121.173004.
Optical analog signal processing has been gaining significant attention as a way to overcome the speed and energy limitations of digital techniques. Metasurfaces offer a promising avenue towards this goal due to their efficient manipulation of optical signals over deeply subwavelength volumes. To date, metasurfaces have been proposed to transform signals in the spatial domain, e.g., for beam steering, focusing, or holography, for which angular-dependent responses, or nonlocality, are unwanted features that must be avoided or mitigated. Here, we show that the metasurface nonlocality can be engineered to enable signal manipulation in the momentum domain over an ultrathin platform. We explore nonlocal metasurfaces performing basic mathematical operations, paving the way towards fast and power-efficient ultrathin devices for edge detection and optical image processing.
光学模拟信号处理作为一种克服数字技术速度和能量限制的方法，已经引起了广泛关注。由于亚波长体积内对光信号的高效操控，超表面为实现这一目标提供了一个很有前景的途径。迄今为止，已经提出超表面来转换空间域中的信号，例如，用于光束转向、聚焦或全息术，对于这些应用，角度相关的响应或非局域性是不希望出现的特征，必须加以避免或减轻。在这里，我们展示了可以通过工程设计超表面的非局域性，从而在超薄膜平台上实现动量域中的信号操控。我们探索了执行基本数学运算的非局域超表面，为边缘检测和光学图像处理等快速、低功耗的超薄器件铺平了道路。
