Image processing is of fundamental importance for numerous modern technologies. In recent years, due to increasing demand for real-time and continuous data processing, metamaterial and metasurface based all-optical computation techniques emerged as a promising alternative to digital computation. Most of the pioneer research focused on all-optical edge detection as a fundamental step of image processing. Metasurfaces have been shown to enable real time edge detection with low to no power consumption. However, the previous demonstrations were subjected to the several limitations such as need for oblique-incidence, polarization dependence, need for additional polarizers, narrow operation bandwidth, being limited with processing in 1D, operation with coherent light only, and requiring digital post-processing. Here, we propose and experimentally demonstrate 2D isotropic, polarization-independent, broadband edge detection with high transmission efficiency under both coherent and incoherent illumination along the visible frequency range using a metasurface based on Fourier optics principles.

图像处理对于许多现代技术至关重要。近年来，由于对实时和连续数据处理的需求不断增加，基于超材料和超表面的全光计算技术成为数字计算的有前途的替代方案。大多数先驱研究都集中在全光学边缘检测上，将其作为图像处理的基本步骤。超表面已被证明能够以低功耗甚至无功耗实现实时边缘检测。然而，之前的演示受到了一些限制，例如需要斜入射、偏振依赖性、需要额外的偏振器、窄操作带宽、受限于一维处理、仅使用相干光操作以及需要数字后处理。在这里，我们提出并通过实验证明了使用基于傅里叶光学原理的超表面，在可见光频率范围内的相干和非相干照明下具有高传输效率的二维各向同性、偏振无关、宽带边缘检测。