On the quest for miniaturization, scientists at the Center for Integrated Nanostructure Physics, within the Institute for Basic Science (IBS, South Korea), in collaboration with researchers from the University of Birmingham and the Korea Advanced Institute of Science and Technology (KAIST), develop credit card-thick, flat lenses with tunable features. These optical devices, made of graphene and a punctured gold surface, could become optical components for advanced applications, such as amplitude tunable lenses, lasers (i.e. vortex phase plates), and dynamic holography.
Metasurfaces are new 2-D materials that can effectively control the electric and magnetic components of light (and other electromagnetic waves) and bend them to bespoken directions. Controlling the beam’s direction can bring out interesting phenomena; the most incredible being the “invisibility cloak effect”, where light waves bypass an object recreating the image beyond the object, as flowing water in a river would bypass a stone.
Published in Advanced Optical Materials, the study presents the properties of a metasurface which works as a convex lens. Specifically, it is made of a gold sheet pierced with micrometer-sized U-shaped holes and covered with graphene. As the shape of common convex lenses allows light to be concentrated on a spot (or focus), think about a magnifying glass which can concentrate a light beam and even start a fire, so the particular pattern of the tiny apertures of the metalenses works by focusing the incoming beam.
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