Physicists would like to make lenses from metamaterials — structures that can have a negative refractive index. Such lenses would tightly focus light over short distances with little or no distortion. So far, researchers have only been able to make crude versions of these lenses from aluminium oxide rods. But Didier Casse, Srinivas Sridhar and their colleagues at Northeastern University in Boston, Massachusetts, say they have built a two-dimensional metamaterials lens from a semiconductor crystal.
The lens was made by carving a lattice into a layered indium gallium arsenic phosphide wafer. It can focus infrared light of the same wavelength as that used in common devices to a spot just 12 micrometres away from its surface. The authors say that the work could lead to smaller, more efficient digital cameras and sensors.
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Materials science: Finding focus. Nature 454, 1033 (2008). https://doi.org/10.1038/4541033b