Roberto Merlin of the University of Michigan has devised a different way of making a superlens that promises to focus light more efficiently, and to an even smaller spot – perhaps 500 times smaller than light's wavelength. Also, compared with conventional metamaterial lenses, this new kind "would definitely be easier to make," Merlin says.
His theoretical study shows that a more effective superlens could be made from a thin plate containing concentric rings made of two different materials. This would be reminiscent of a tree trunk and its annual growth rings. The rings would alternate between material that blocks light – such as metal – and rings that let light through, like silicon or glass.
Overall, the set of rings should "sculpt" light emerging from the plate to creating a focused point of light. And using this method ought to be much more flexible than other ways of making superlenses, Merlin says. In addition to focusing light into a point, "I could make a line," he adds. "I could probably write 'University of Michigan'."
In metamaterial lenses, "loss [of light] is unavoidable", says Willie Padilla of Boston College in Massachusetts. "The approach that Merlin is proposing can avoid these losses."
Light spectrum wavelengths
violet 380–450 nm
blue 450–495 nm
green 495–570 nm
yellow 570–590 nm
orange 590–620 nm
red 620–750 nm
Spots 500 times less would put green to violet light at 1 nanometer.
Ultraviolet LEDs and lasers with 240 nm would make spots 0.48 nanometers.
Applications include higher density data storage on optical discs and more precise lithography – the process used to make computer chips.
With the new technology, a CD could hold up to one hundred times more information by using terahertz radiation rather than visible light, even though the length of a terahertz wave is about 1000 times longer.