when the meta materials held got its start a bit more than a decade ago, meta-atoms tended to be macroscopic: centimeter size metallic split rings and wires printed on standard circuit boards. But these structures were so large they could act only on longer- wavelength radiation, in the microwave part of the spectrum. To make metamaterials that can act on visible light, which has a wavelength range of roughly 400 to 750 nanometers, the atoms" must he on the order of 100 to 200 nanometers or smaller.