By shining lasers onto a tiny screen roughly as wide as a pencil-top eraser, scientists at Meta have created an ultrathin, high-definition flat-panel display they suggest might be used in augmented reality applications.
Flat-panel displays are now commonplace, often illuminated by LEDs. When contemplating the next step beyond these displays, scientists have explored replacing the LEDs with lasers. Ideally, laser-based displays can offer superior brightness and a wider range of colors than conventional LED displays, researchers at Meta say.
“High brightness is important particularly for see-through and outdoor applications, such as augmented reality use cases,” due to the bright lighting conditions in which people often find themselves, explains Guohua Wei, an optical scientist at Meta’s Reality Labs in Redmond, Wash. “Rich color provides a much better user experience, as we see in traditional cinemas.”
However, laser displays typically rely on complex, bulky optical systems to deliver laser light precisely where it is needed on screens. Previous attempts to develop flat-panel laser displays have required complicated laser arrays or low-throughput fabrication methods, greatly limiting their performance and scalability, the researchers say.
Now, the team at Meta has developed a flat-panel laser display only 2 millimeters thick. With it, they developed a prototype see-through augmented reality system that could blend virtual images with real-world scenes in an office environment. The photonic chip driving the new display may also one day be used in everything from smartphone screens to slim-panel 3D holography.
“After three years of research and thousands of illuminator chips prototyped, we are happy to have the opportunity to share with the tech community the results of our team’s work,” says Giuseppe Calafiore, head of the augmented reality waveguides group at Meta’s Reality Labs.
Photonic Chip Slims Meta’s Display
At the heart of the new display is a centimeter-scale photonic integrated circuit. This combines thousands of components with different optical functions onto a single photonic chip, avoiding the need for the complex, bulky optical systems required with conventional optics. “It’s an integrated optical chip that can generate almost any arbitrary optical function,” Calafiore says.
The new display weds the photonic chip with a 5- by 5-millimeter liquid-crystal-on-silicon (LCoS) panel, which has a resolution of 1,920 by 1,080 pixels. The resulting device is less than one-eightieth the thickness of conventional LCoS displays while achieving 211 percent of the color gamut.
The new photonic chip was fabricated using standard CMOS-compatible processes, making it scalable for mass production, the scientists note. The devices may one day find use in a wide range of new kinds of displays, including slim-panel holographic displays, high-resolution light-field displays, and more, they add.
“This work could pave the way to a future where photonic integrated circuits create the brightest, most compact new kind of displays,” Calafiore says.
Calafiore notes that current LCoS displays are limited to pixel sizes of about 3 micrometers. This could mean any system based on LCoS—including the new display—may fall behind competitors in the augmented reality market, such as micro-LEDs, unless LCoS research is not pushed more aggressively.
The scientists detailed their findings 20 August in the journal Nature.
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Charles Q. Choi is a science reporter who contributes regularly to IEEE Spectrum. He has written for Scientific American, The New York Times, Wired, and Science, among others.
