A left-handed sandwich. Two copper grids flank the left-handed lens (silver grid).

Southpaw Lens Rules the Waves

For centuries, microscopes, eyeglasses, and magnifying glasses have been limited by the laws of optics: No matter how good their lenses, details smaller than a wavelength of light are lost. Undaunted, physicists have built a different breed of lens with the potential for perfect resolution.

The new lens, which George Eleftheriades and Anthony Grbic of the University of Toronto describe in an upcoming issue of Physical Review Letters, focuses microwaves--long-wavelength radiation that falls next to radio waves in the electromagnetic spectrum. By embedding a wire grid studded with capacitors and inductors in a flat plane of plastic, the researchers created a lens with a so-called negative refractive index, also called a left-handed lens. Waves traveling through it bend in the opposite direction than they would in a conventional material.

The left-handed lens achieves super-resolution by resurrecting waves that carry the subwavelength details of an object. Such waves usually fizzle out before they pass through a lens. But the Toronto group's lens traps and amplifies them, allowing it to distinguish objects just 1/6 of a microwave wavelength apart.

The new technique "smashed the barrier; it crashed through the glass ceiling," says John Pendry, a physicist at Imperial College London. In 2000, Pendry predicted that left-handed materials would make possible marvels such as completely flat lenses with perfect resolution and zero loss (Science, 10 November 2000, p. 1066). In February, physicists at the Institute for Theoretical and Applied Electromagnetics in Moscow announced a super-resolving lens, but their technique required the object to be almost touching the lens, making it impractical for real-life applications. The new lens overcomes that limitation.

Related sites
George Eleftheriades's Web site
More on left-handed materials

Posted in Physics