Scientists create the thinnest lens on Earth using quantum physics

A quantum phenomenon has allowed scientists to develop a lens just three atoms thick, the thinnest ever made.

Remarkably, the innovative approach allows most wavelengths of light to pass through directly – a feature that could see it have huge potential in fiber optic communications and devices such as augmented reality glasses.

The researchers who invented the lens, from the University of Amsterdam in the Netherlands and Stanford University in the US, say their innovation will advance research into lenses of this type, as well as miniature electronic systems.

«The lens can be used in applications where the view through the lens does not have to be disturbed, but a small part of the light can be touched to collect information,» says Jorik van de Groep, a. nanoscientist at the University of Amsterdam.

Instead of using the curved surface of a transparent material to bend the light in a refraction process, the incoming waves are instead focused by a series of grooved edges using diffraction.

The technology, known as a Fresnel lens or zone plate lens, has been used for centuries to produce thin, lightweight lenses like those used in glasses.

To give the technique a quantum boost, the research team etched concentric rings into a thin layer of a semiconductor called tungsten disulfide (WS₂). When WS₂ absorbs light, its electrons move in a precise way that leaves a gap that can be considered a kind of particle in its own right.

Together, the electron and its ‘hole’ are form what is known as an excitonwhich has properties that help efficiently concentrate very specific wavelengths of light while allowing other wavelengths to pass through unchanged.

The size of the rings and the distance between them allowed the lens to focus the red light at a distance of 1 millimeter. The team found while the lens works at room temperature, at lower temperatures its focusing capabilities become even more efficient.

Next, the researchers want to conduct more experiments to see how the behavior of the exciton can be further manipulated to improve the efficiency and capability of the lens. Future studies could include optical coatings that can be placed on other materials, for example, as well as changes in electrical charge.

«Excitons are very sensitive to the charge density in the material, and therefore we can change the refractive index of the material by applying a voltage,» says van de Groep.

The research was published in Nano Letters.