“This technology is potentially revolutionary because it works in the visible spectrum, which means it has the capacity to replace lenses in all kinds of devices – from microscopes to cameras and displays and cell phones,” said Professor Federico Capasso and senior research fellow Vinton Hayes. “In the near future, metalenses will be manufactured on a large scale at a small fraction of the cost of conventional lenses, using the foundries that mass produce microprocessors and memory chips.”
In order to focus red, blue and green light, the team needed a material that wouldn’t absorb or scatter light. The solution was to deposit an array of high aspect ratio titanium dioxide nanofins to create a metasurface.
The team designed the array to resolve a structure smaller than a wavelength of light, around 400nm across. At these scales, the team claims, the metalens could provide better focus than a state-of-the art commercial lens.
Wei Ting Chen, a postdoctoral fellow in Prof Capasso’s lab, noted: “Our lens can be produced in a single step: one layer of lithography and you have a high performance lens, with everything where you need it to be.”
While potential applications include smartphones and cameras, the team believes the metalens may also find use in virtual reality and augmented reality systems.
Mohammadreza Khorasaninejad, a postdoctoral fellow in the Capasso lab, said: “Any good imaging system right now is heavy because the thick lenses have to be stacked on top of each other. This technique reduces weight and volume and shrinks lenses to thinner than a sheet of paper. Imagine the possibilities for wearable optics, flexible contact lenses or telescopes in space.”