A simple-to-make 鈥渟uperlens鈥� can focus 10 times more sharply than a conventional lens. It could shrink the size of features on computer chips, or help power gadgets without wires.
No matter how powerful a conventional lens, it cannot focus light down to more than about half its wavelength, the 鈥溾��. This limits the amount of data that can be stored on a CD, and the size of features on computer chips.
Researchers have devised ways to beat the diffraction limit before, using bizarre 鈥溾�� that are hard to make, and which are also the basis of prototype 鈥渋nvisibility cloaks鈥�.
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But such complex mixes of material stuffed with tiny loops of metal and precisely-shaped holes are unlikely to become a mass-production technology.
Simply super
, Lei Jiang and at the University of Michigan in Ann Arbor, US, have now successfully made a much simpler design, first theorised last year.
The new lens is a 127-micrometer-thick plate of teflon and ceramic with a copper topping. 鈥淭he beauty of these is that they鈥檙e planar,鈥� Grbic says, 鈥渢hey鈥檙e easy to fabricate.鈥� The lenses can be made through a single step of photolithography, the process used to etch computer chips.
By selectively etching away the copper, Grbic and colleagues created many capacitors sandwiched together. Capacitors are typically used in electronics for storing electric charge for short periods.
In the lens, the capacitors instead interact directly with electromagnetic waves like light. This sets up currents in the capacitors that focus the waves passing through the lens into a point 20 times smaller than their wavelength. That is 10 times tighter than a conventional lens can achieve, hampered by the diffraction limit.
Microwave trials
The team鈥檚 current prototype works on microwaves, which are easier to focus because they have longer wavelengths than visible light. Simply making capacitors of different sizes would allow the lens to focus other frequencies, including visible and infrared light, says Grbic.
Grbic and colleagues have a variety of uses for their new lenses planned, including focusing light into smaller spots during photolithography to etch smaller features onto computer chips.
The lenses could also help refine a technique to transfer power wirelessly developed in 2006. The new lenses could create more energy-dense beams of the electromagnetic waves used to transfer power, Grbic says.
鈥泪苍驳别苍颈辞耻蝉鈥�
The theory behind these lenses is 鈥渋ngenious,鈥� says of Imperial College London, UK, who in 2006 proved invisibility cloaks could be possible. 鈥淭his is an important step forward in sub-wavelength imaging with considerable potential applications,鈥� he adds.
of the University of Pennsylvania in Philadelphia, US, agrees, saying the new design has 鈥渆xciting potential.鈥� But the more complex metamaterial lenses will likely be more applicable to more diverse applications, he adds.
Journal reference: (DOI: 10.1126/science.1154753)
