LAUSR

Description Resonant metasurfaces pave the way for more compact sources of pure chiral light Chirality describes the inherent “handedness” of many physical systems—from the left-handed amino acids that form the building blocks of life to the right-handed spiral staircases in the medieval castles of Europe. Light, too, can be chiral, manifesting as right-circular or left-circular polarization states, in which the electric field rotates clockwise or anticlockwise in time and traces out a spiral trajectory as it propagates through space. Despite the impressive technological progress since the discovery of light’s chirality hundreds of years ago, the practical challenge of producing chiral light from a compact source remains elusive. This is because the chiral interaction of light and matter is typically very weak and thus requires the use of bulky materials. On page 1215 of this issue, Zhang et al. (1) demonstrate a metasurface that acts as a tiny and controllable source of pure and directional chiral light.