Negative refractive index material created

German scientists have created a metamaterial with a negative refractive index for far red light:

The trick is to assemble an array of electronic components that resonate with the electric and magnetic fields of the light waves as they pass through. These materials are unlike any conventional substance, hence the name "metamaterial". Pendry suggested that an array of coils and wires much smaller than the wavelength of light would do the trick and first demonstrated the idea for radio waves with a frequency between 15 and 20 megahertz.

Later experiments extended the technique to shorter wavelengths, first into the microwave region and later the infrared. Now Gunnar Dolling at the University of Karlsruhe in Germany, and colleagues, have demonstrated the effect at 780 nanometres - the long-wavelength end of the red spectrum - by scaling down a structure he had developed for infrared wavelengths.

Dolling's metamaterial is made by depositing a layer of silver on a glass sheet, covering this with a thin layer of nonconducting magnesium fluoride, followed by another silver layer, forming a sandwich 100 nm thick. Dolling then etched an array of square holes through the sandwich to create a grid, similar to a wire mesh.

Dolling determined the refractive index of the material by measuring the "phase velocity" of light as it passed through. His measurements show the structure has a negative refractive index of -0.6 for light with a wavelength of 780 nm.

This value drops to zero at 760 nm and 800 nm, and becomes positive at longer and shorter wavelengths. Previously, the shortest wavelength at which a negative refractive index had been demonstrated was 1400 nm.

They speculate that this material could be used in lens or to create invisibility cloaks. My suspicion is such things are a long way off, but it is still pretty damn cool.

Hat-tip: Slashdot.

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Thanks for mentioning "phase velocity." I gave such a bad description to my Physics professor wife, that she assumed I meant that the veloicity of light increased inside the material. I said that the speed of light IS slighly greater between two closely separated parallel metal plates by the Casinmir effect, and that the German work cited was a surface effect, and waved my hands about Snell's Law.

Phase velocity. Of course. Now the next Harry Potter movie can have a genuine cloak of invisibility, right?

Well, see my old discussion of invisibility in my 12-year-old web domain:

"Perhaps the first true modern Invisibility story was "The Invisible
Gentleman", by James Dalton [1833] -- but it was clearly Fantasy, there
being several twists to ensure that the hero gains nothing from his
condition (according to "The Encyclopedia of Fantasy", John Clute & John Grant,
St.Martin's, 1997, p.503). "The Horla" by Guy de Maupassant (1887) is a
recognized literary classic, which happens to be about an invisible
monster...."

http://www.magicdragon.com/UltimateSF/thisthat.html#invisibility