A research team at Maryland's A. James Clark School of Engineering comprised of Professor Christopher Davis, Research Scientist Igor Smolyaninov, and graduate student Yu-Ju Hung, has used plasmon technology to create the world's first invisibility cloak for visible light. The engineers have applied the same technology to build a revolutionary superlens microscope that allows scientists to see details of previously undetectable nanoscale objects.

Generally speaking, when we see an object, we see the visible light that strikes the object and is reflected. The Clark School team's invisibility cloak refracts (or bends) the light that strikes it, so that the light moves around and past the cloak, reflecting nothing, leaving the cloak and its contents "invisible."

The invisibility cloak device is a two-dimensional pattern of concentric rings created in a thin, transparent acrylic plastic layer on a gold film. The plastic and gold each have different refractive properties. The structured plastic on gold in different areas of the cloak creates "negative refraction" effects, which bend plasmons—electron waves generated when light strikes a metallic surface under precise circumstances—around the cloaked region.

This manipulation causes the plasmon waves to appear to have moved in a straight line. In reality they have been guided around the cloak much as water in a stream flows around a rock, and released on the other side, concealing the cloak and the object inside from visible light. The invisibility that this phenomenon creates is not absolutely perfect because of energy loss in the gold film.