Magazine article Science News

Closer to Vanishing: Bending Light as a Step toward Invisibility Cloaks

Magazine article Science News

Closer to Vanishing: Bending Light as a Step toward Invisibility Cloaks

Article excerpt

Harry Potter fans, do not despair! Invisibility cloaks may be a long shot, but last year physicists demonstrated technology that might someday hide you from radar. Now, two groups of researchers have taken steps toward performing the same trick with visible light.

Light rays passing from one transparent material to another generally refract, or change direction. That's why a pencil looks broken when partially submerged in water. Recently, physicists have begun to explore materials with a characteristic called negative refraction. If water had that property, the underwater half of the pencil would appear to stick out above the surface.

The first demonstration of negative refraction used materials that displayed the effect at one particular microwave wavelength. Last year, researchers showed that a suitably shaped piece of negatively refracting material could hide an object by guiding microwaves around it (SN: 7/15/06, p. 42).

A team led by Henri Lezec of the California Institute of Technology in Pasadena has now achieved negative refraction for visible light over a spectrum of blues and greens.

Lezec's team built a micrometer-size prism of layered metals perforated by a maze of nanoscale channels. Light striking the prism transforms into plasmons, two-dimensional waves in which electromagnetic fields displace electrons along the metal surfaces. Guided by the nanochannels, the plasmons travel through the prism, turning back into light when they emerge on the other side. …

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