Optical cross-correlation analog computing based on dielectric metasurface at mid-infrared wavelengths

Compared to inefficient, energy-intensive digital computing, optical analog computing has significant advantages in terms of computational speed and power consumption. Traditional optical analog computing is typically based on Fourier lenses and spatial frequency filters, which are bulky and difficult to integrate. These disadvantages can be overcome by replacing Fourier lenses and spatial frequency filters in traditional optical analog computing via a metasurface. We showcase a real-time compact optical cross-correlation analog computing based on a dielectric metasurface. An extra phase profile is introduced in the metasurface to approximate the Fresnel diffraction integral as the Fourier transform to realize a more compact scheme. The optical cross-correlation analog computing is derived by directly modulating the impinging optical field. A reference circular pattern of a circular target is highlighted recognized and identified by the operation. The recognition accuracy was analyzed by comparing the recognition peaks with the shifted center of the circle, showing that the operation is affected by the side flap of the other circle pattern in the background. Optical analog computing with a compact and powerful kernel may find potential solutions for bio-detection, pattern recognition, information retrieval, and electron tomography.