Tapering Waveguide Captures a Rainbow

SubComdTaco passes along news of researchers in the US who have trapped a rainbow in a tapering waveguide. The research is described (PDF) on the arXiv. "In 2007, Ortwin Hess of the University of Surrey in Guildford, UK, and colleagues proposed a technique to trap light inside a tapering waveguide [made of metamaterials]... The idea is that as the waveguide tapers, the components of the light are made to stop in turn at ever narrower points. That's because any given component of the light cannot pass through an opening that's smaller than its wavelength. This leads to a 'trapped rainbow.' ... Now Vera Smolyaninova of Towson University in Baltimore, Maryland, and colleagues have used a convex lens to create the tapered waveguide and trap a rainbow of light. They coated one side of a 4.5-mm-diameter lens with a gold film..., and laid the lens — gold-side down — on a flat glass slide which was also coated with film of gold. Viewed side-on, the space between the curved lens and the flat slide was a layer of air that narrowed to zero thickness where the lens touched the slide — essentially a tapered waveguide. When they shone a multi-wavelength laser beam at the... gilded waveguide, a trapped rainbow formed inside. This could be seen as a series of colored rings when the lens was viewed from above with a microscope: the visible light leaked through the thin gold film."

Comments

What they're really researching

[Broofa]

Dr. Hess was later quoted as saying, "While we're obviously pleased with our success so far, we won't be satisfied until we've trapped not only the rainbow, but the leprechaun and pot of gold as well. Until then, we remain disturbingly dependent on grant money for our research."

Amazing work, but brings to mind a quote

[Dr. Eggman]

"If humans could put Rainbows in a Zoo, they would."
--Bill Watterson, via Hobbes in Calvin and Hobbes.

Re:What happens when the laser is turned off?

[amorsen]

Interesting theory, but where does this energy go ? Is it converted to sound, heat, mass, or some other form ?

Heat.

And if we could completely "sap all the energy" away from the beam, wouldn't this imply we could create 100% effecient solar cells ?

As long as you're happy with heat as output, 100% efficient solar cells are quite trivial.