ETH Zurich builds pixels that emit and detect light

Key Takeaways

• ETH Zurich researchers developed pixels that can both emit and measure light using Fourier analysis
• The technology could enable two-way screens, holographic displays, and optical communication systems
• Fourier pixels control amplitude, phase, and polarization on a single pixel surface

A team at ETH Zurich has created a new type of pixel that can both emit and measure light. The breakthrough, published in Nature, could eventually merge displays and cameras into a single surface.

Traditional pixels do one job. Display pixels illuminate. Camera sensor pixels capture. David Norris, professor at ETH Zurich's Optical Materials Engineering Laboratory, led research that combines both functions into what the team calls Fourier pixels.

How Fourier pixels work

The technique measures light wave interference patterns over a metallic surface. By analyzing these patterns using Fourier transforms, the researchers can generate pixels that create and detect three properties of optical fields: amplitude, phase, and polarization.

A Fourier transform takes a complex signal and breaks it into its component frequencies. Applied to light, this mathematical technique lets the researchers represent spatial frequency rather than just brightness at a single point.

“Thanks to the fact that the relevant surface profiles of the pixels can be determined using Fourier analysis, we can combine the control and analysis of amplitude, phase and polarisation on a single pixel.”

— Sander Vonk, post-doctoral researcher, ETH Zurich

This control over multiple light properties distinguishes Fourier pixels from existing display or sensor technology. Current devices treat these as separate engineering problems requiring separate hardware.

What could bidirectional pixels enable?

The research paper outlines several potential applications. Two-way screens could display images while simultaneously capturing what's in front of them. No more notches, holes, or under-display cameras struggling with image quality.

Holographic displays represent another possibility. Because Fourier pixels control phase and polarization alongside brightness, they could create more sophisticated light fields than current display technology allows.

The researchers also point to optical communication systems and quantum information processing as potential use cases. Both fields require precise control over light properties at the pixel level.

What comes next for this research?

Norris expects the near-term focus will be building Fourier pixels into a matrix. A single bidirectional pixel demonstrates the principle. An array of them could form a functional camera-display hybrid.

The gap between lab demonstration and commercial product remains wide. The research team, which included Yannik M. Glauser, David B. Seda, Hannah Niese, and several other collaborators, has proven the concept works. Manufacturing it at scale, at consumer price points, presents different challenges.

Display technology typically takes years to move from research paper to production. Quantum dot displays, for instance, spent over a decade in development before reaching consumer TVs. OLED followed a similar timeline.

Why hardware makers should pay attention

Smartphones ship over 8 billion camera units annually. Every one of those devices makes a design tradeoff between screen real estate and camera placement. A display that captures images eliminates that tradeoff.

The $190 billion display market has cycled through several technology generations: CRT to LCD to OLED. Each transition rewarded early movers and punished companies that held onto old technology too long. Bidirectional pixels could trigger another such shift.

For now, this remains academic research. But the physics works. The math works. The engineering challenge is scaling it up.

Frequently Asked Questions

What is a Fourier pixel?

A Fourier pixel is a new type of picture element that can both emit and measure light. It uses mathematical Fourier analysis to control the amplitude, phase, and polarization of optical fields on a single surface.

When will bidirectional displays reach consumers?

The ETH Zurich research is still at an early stage. The next step is building pixel arrays. Based on typical display technology timelines, consumer products could be 5-10 years away.

Could this eliminate front-facing cameras on phones?

Potentially. If displays can capture images while showing them, the separate camera sensor becomes unnecessary. This would let phone makers use the entire front surface for display.

What other applications could Fourier pixels enable?

The research paper cites holographic displays, optical communication systems, and quantum information processing as potential applications beyond camera-display integration.

Source: www.theregister.com