Meta-optical and thin film devices for all-optical information processing

All-optical spatial frequency filtering has a long history with many applications now commonly replaced digital alternatives. Although optical approaches are attractive in that they minimize energy requirements and images can be manipulated real time, relatively bulky compared to the compact electronic devices ubiquitous. With emerging interest nanophotonic all-optical information processing, these enhancing performing phase visualization attracting significant interest. Metasurfaces have been demonstrated as tailored alternatives conventional filters, but utilizing sensitivity of thin film also potential form basis for ultracompact image processing. There are, however, challenges remaining realize this promise. This review summarizes current status research rapidly growing field, places it context filtering, assesses prospects future directions.