Now You See Me…

On the left is a schematic of the first 3-D “fishnet” metamaterial that can achieve a negative index of refraction at optical frequencies. On the right is a scanning electron microscope image of the fabricated structure, developed by UC Berkeley researchers. The alternating layers form small circuits that can bend light backwards. (Image by Jason Valentine, UC Berkeley)

Researchers at the University of California, Berkeley have discovered how to bend light backward by creating a novel fishnet-shaped nanomaterial. Though it sounds far fetched, the material might provide the basis for cloaking devices that render objects invisible to the eye, according to UC Berkeley doctoral student Jason Valentine, who coauthored a paper on the research with applied physicist Xiang Zhang for Science magazine. Potential medical applications of the technology include ultrahigh-resolution imaging systems that could peer within human cells to the molecular or possibly even atomic level.

The breakthrough was made possible by stacking 21 layers of silver and magnesium fluoride on a quartz substrate. The researchers used an ion beam to drill holes through the layers and then made the stack into a prism by cutting it at an angle. When red light was shined at the material, it demonstrated negative refraction, according to Valentine. Used to measure the bending of light as it passes through one medium into another, the refractive index is positive for all objects in the natural world. For instance, the refractive index of air is roughly 1.0. For water, on the other hand, the value is about 1.3. The difference between the two values makes objects submerged in water appear closer to the surface than they actually are. If water had a negative refractive index, a fish swimming in a pond would appear to hover above the water’s surface, as depicted below:

Tags: Materials, medtechinsider, Nanotechnology and Microtechnology, Research, Technology