Pixels are fundamental components of modern technology. They form the images displayed on TVs, smartphones, and computer screens, and are essential for digital cameras to capture photographs by sensing incoming light. Historically, a pixel could only serve one function—either producing light for display or detecting light for image capture, but not both simultaneously.
Now, researchers at ETH Zurich have pioneered a groundbreaking type of pixel capable of performing both functions. This advancement could someday enable devices that function as both cameras and displays simultaneously. Instead of separate screen layers and camera sensors, future gadgets like smartphones, tablets, or wearable tech might integrate these capabilities into a single, unified layer.
The innovative technology is rooted in the natural behavior of light, known as interference. Light waves travel in oscillating patterns, and when different waves intersect, their interaction depends on their alignment. If the peaks and troughs align, the waves reinforce each other; if out of sync, they diminish each other. This phenomenon creates colorful patterns we see in nature, such as soap bubbles and oil slicks.
The ETH Zurich team mastered control over this interference with extraordinary precision. They crafted tiny, wave-shaped structures on each pixel’s surface, accurate to only a few nanometers—billionths of a meter. When light enters these specially designed pixels, it first transforms into a surface-bound wave, then reverts back to normal light. Thanks to the precise surface patterns, the researchers can dictate exactly how the light behaves as it exits.
Unlike traditional pixels, these “Fourier pixels” can modulate not only the intensity of light but also other key properties. One of these is polarization—the direction in which a light wave vibrates—which is widely used in sunglasses, camera filters, and advanced communication systems. The new pixels can both generate and detect various polarization states.
They can also manipulate the phase of light, determining the position within its repetitive cycle. Controlling phase enables the creation of unique light shapes, such as doughnut-shaped beams with a dark central hole, useful in scientific and technological applications. Furthermore, these pixels are compatible with multiple colors, allowing for the generation of full-color images.
Interestingly, the same pixels can operate in reverse. Instead of shaping outgoing light, they can analyze incoming light by measuring its brightness, phase, and polarization. They achieve this by comparing reflected or transmitted light with a reference wave, then interpreting the interference pattern to extract the light’s properties. Due to their sophisticated design and the application of Fourier analysis—which transforms complex data into understandable components—they can perform these calculations internally, without needing external computers.
The researchers see wide-ranging potential for this technology, including applications in display screens, digital imaging, fiber-optic communication, medical diagnostics, and scientific research instruments. Their next objective is to develop large arrays of these intelligent pixels. If successful, this could lead to compact devices capable of both capturing and displaying images in a single integrated system, opening new frontiers in consumer electronics and optical innovation.
