Pixels control and analyze the light in displays—they’re part of the reason you’re reading this sentence right now. But it’s usually one or the other. A pixel either monitors or analyzes, but not at the same time.
Researchers from ETH Zurich in Switzerland have succeeded in creating a new type of pixel that can do both at the same time. This hypercharged pixel, called a Fourier pixel, can generate and sense arbitrary light fields and use the pixel’s full potential to carry information by controlling light intensity, oscillation phases, and polarization. The team based their findings on a paper It was published yesterday in the journal Nature.
Looking ahead, the team expects that these pixels could support next-generation technologies such as holographic displays, augmented reality, or devices that can actively adjust their output based on what they detect. The technology could lead to camera-display devices that both display images and sense incoming light.
“The Fourier pixel extends the functionality of conventional pixels by using surface waves interacting with a precisely designed wavy microstructure,” co-authors of the study said. Yannick Glauser and Sander Wonk Gizmodo reported. “In this sense, it’s not just an intensity pixel, but a compact optical element for full-field light control.”
“This ability is important because light can carry a lot of information if we can fully control all its attributes,” he said. David Norrisoptical physicist who co-authored the study and led the team.
Unlocking the potential of light
Currently, pixels—short for “picture elements”—locally measure or emit light intensity, working with only one light property, according to the paper. But in recent years, researchers have explored ways to interfere with various properties of light in search of a new generation of information technology, e.g Microsoft’s Silica project.
“As optical technologies continue to improve, whether in display, sensing, communication, or imaging, we will need devices that can handle the full complexity of light,” explained Glauser and Vonk, Ph.D. and postdoctoral researchers in optics. Fourier pixels, which offer bidirectional control of light, represent a step in that direction, they added.
Waves of light
Fourier pixels are based on several fundamental phenomena in optical physics. They are called that because the mathematical principles were developed by the mathematician Joseph Fourier, Norris explained. In previous workbased on Fourier’s work, the team found a technique to create arbitrary wavy surfaces.
Norris added that this was a key component of Fourier’s pixels, as they indicated to the team a way for precisely machined surfaces to interact with different properties of light. For the latest results, the researchers expanded on this idea. In particular, they tested whether these scattered light waves could be converted into guided waves and an optical pattern carrying the relevant information.
In other words, a pixel—here, a sculptural part of an interface—can both create and sense the basic properties of light (amplitude, oscillation phases, and polarization) to represent images or data. In addition, the design of these pixels requires relatively simple mathematics, making them “flexible and convenient for potential applications,” Norris said.
Pixels of the future
According to the university, Fourier pixels can help two-way camera displays, where each pixel both emits and detects light. Glauser and Vonk explained to Gizmodo that this new generation of devices “can not only display an image, but also sense ambient light or how the user interacts with it.”
For the latest work, the team managed to create very small arrays of Fourier pixels, Norris acknowledged, adding that such camera displays are currently in the realm of speculation. But it’s an interesting step in an unexplored direction. In theory, Fourier pixels could be useful in designing “adaptive optics, holographic displays, augmented reality, optical communications, or devices that actively adjust their output based on what they detect,” Glauser and Vonk said.
“Personally, I think the combination of simple math and precise fabrication is pretty cool,” Norris said. “The math predicts a crazy wavy pattern for a certain optical output. We go and make that pattern on the surface and the device immediately produces the result we want. In other words, the math really works!”
