Researchers from The University of Osaka propose a compact LED design that directly emits circularly polarized light, potentially simplifying optical devices

Osaka, Japan – From 3D movie screens to augmented-reality devices, many modern technologies rely on our ability to manipulate light. Doing so in a cost-effective and efficient way, however, is often a formidable task.

In an article published this month in Optics Letters, researchers from The University of Osaka announced a new light-emitting diode (LED) design that may help shrink complex optical systems into much smaller devices. The LED produces circularly polarized light using a built-in nanostructured surface, eliminating the need for bulky external optical components.

Circularly polarized light, whose electric field rotates like a corkscrew as it travels, is essential for technologies such as 3D displays, advanced imaging systems, and quantum communication tools. Traditionally, generating this kind of light requires optical components such as polarizers and special plates that modify the light’s phase. However, these components make devices larger, more complex, and harder to integrate.

“Our goal is to simplify the way circularly polarized light is produced,” says corresponding author Shuhei Ichikawa. “By integrating polarization control directly into the LED with a specially designed metasurface, we remove the need for additional optical components.”

This metasurface consists of extremely small gallium nitride nanopillars directly arranged in a carefully designed pattern on the surface of a semiconductor LED. The nanoscale structures manipulate the phase of light so that one circular polarization state is selectively transmitted while the opposite polarization is suppressed.

“Computer simulations show that the design can produce strong circularly polarized light while allowing about 35% of the LED’s light to pass through the nanostructured surface,” explains Shuhei Ichikawa, senior author. “That level of efficiency approaches the theoretical maximum of 50%.”

Unlike many previous circularly polarized LEDs, which utilize organic materials or complex spin-based systems, the new design uses robust inorganic materials, which could help enable more durable and practical circularly polarized light sources.

“Theoretically, there is a tradeoff between LED efficiency and polarization degree, which measures the extent to which one polarization state dominates,” says Ichikawa. “What is very exciting about this device is that we have found a way to maintain high levels of both.”

In the future, such compact circularly polarized light sources could simplify the optical hardware used in virtual reality headsets, high-resolution 3D displays, and emerging photonic technologies. Thanks to the team’s research, the future of smaller and more efficient light-based devices is definitely looking bright.
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The article, “Circularly polarized (0001) InGaN-based LED integrated with GaN metasurface,” was published in Optics Letters at DOI: https://doi.org/10.1364/OL.587468

About The University of Osaka
The University of Osaka was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world. Now, The University of Osaka is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.
Website: https://resou.osaka-u.ac.jp/en