Negative Refraction of Visible Light Demonstrated
However, physicists have thought that, if new optical materials could be constructed at the nanoscale level in a certain way, it might be possible to make the light bend at the same angle, but in the opposite direction. In other words, the pencil angled into the water would appear to bend backward as we looked at it.
Dionne, one of the lead authors, says that the breakthrough is made possible by the Atwater lab's work on plasmonics, an emerging field that "squeezes" light with specially designed materials to create a wave known as a plasmon. In this case, the plasmons act in a manner somewhat similar to a wave carrying ripples across the surface of a lake, carrying light along the silver-coated surface of a silicon-nitride material, and then across a nanoscale gold prism so that the light reenters the silicon-nitride layer with negative refraction.
"Maybe you could create a superlens that can beat the diffraction limit," says Dionne. "You might be able to see DNA and protein molecules clearly just by looking at them, without having to use a more complicated method like X-ray crystallography."
Atwater, who is the Howard Hughes Professor and professor of applied physics and materials science at Caltech, says the plasmonic technique indeed has potential for a compact "perfect lens" that could have a huge number of biomedical and other technological applications. "Once the light coming from a nearby object passes through the negative-refraction material, it would be possible to recover all the spatial information," he says, adding that the loss of this information is why there is ordinarily a limit to the size of an object that can be seen in a microscope.
Even more tantalizing is the possibility of an optical "invisibility cloak" device that would surround an object and bend light in such a way that it would be perfectly refocused on the opposite side. This would provide perfect invisibility for the object inside the cloak, in a manner similar to the cloaks used by Harry Potter or the Klingons in the old Star Trek television series.
"Of course, anyone inside the cloak would not be able to see out," Atwater says. "But maybe you could have some small windows," Dionne adds.
Source: Caltech