Dielectric metasurface based advanced image processing

We numerically and experimentally demonstrate an optical image processing technique in the form of edge detection of an object by exploring the angular selectivity of dielectric metasurfaces. By taking the advantages of resonant dielectric metasurfaces with spatial dispersion property, we efficiently filter-out the lower k-vector components of an image and only allow the higher k-vectors resulting in displaying the silhouettes of an object. We have considered dielectric amorphous silicon (a-Si) nanodisk with hexagonal structure interface which provides nearly zero transmission for lower k-vectors and near-unity transmission for higher k-vectors at the operating wavelength of 1550 nm. The proposed metasurface has been fabricated using electron beam lithography followed by a lift-off process. Our results suggest a new way to realize the effective edge detection with dielectric metasurfaces and open new opportunities for ultracompact optical image processing devices, having various applications in microscopy.