Nanowerk January 16, 2023
Ultrathin optical metasurfaces have been recently explored to process large images in real time, in particular for edge detection. They can be tailored to solve complex mathematical problems in the analogue domain, although these efforts have so far been limited to guided-wave systems and bulky set-ups. An international team of researchers (the Netherlands, USA – University of Pennsylvania, City University of New York) developed an ultrathin Si metasurface-based platform for analogue computing that was able to solve Fredholm integral equations of the second kind using free-space visible radiation. A Si-based metagrating was inverse-designed to implement the scattering matrix synthesizing a prescribed kernel corresponding to the mathematical problem of interest. A semitransparent mirror was incorporated into the sample to provide adequate feedback. Visible wavelength operation enabled a highly compact, ultrathin device that could be interrogated from free space, implying high processing speeds and the possibility of on-chip integration…read more. TECHNICAL ARTICLE
Kernel design. Credit: Nature Nanotechnology (2023)Â