The Power of Pixelation: Metasurface Technology Displays 36 High-Resolution Images on a Single Surface

In today’s world, technologies that harness the power of light are omnipresent – from smartphones and TVs to credit cards. Many of these innovations rely on holography, but conventional methods have long faced limitations, particularly in displaying multiple images on a single screen without compromising image quality. A groundbreaking breakthrough has recently been made by a research team at POSTECH (Pohang University of Science and Technology), led by Professor Junsuk Rho.

The team’s pioneering metasurface technology can display an astonishing 36 high-resolution images on a surface thinner than a human hair. This achievement is a testament to the incredible advancements in nanostructure engineering. The researchers employed silicon nitride, a robust material with excellent optical transparency, to fabricate nanometer-scale pillars – known as meta-atoms – that enable precise control over light as it passes through.

One of the most striking aspects of this technology is its ability to project entirely different images depending on both the wavelength (color) and spin (polarization direction) of light. For example, left-circularly polarized red light might reveal an image of an apple, while right-circularly polarized red light could produce an image of a car. This technique allowed the researchers to encode 36 images at 20 nm intervals within the visible spectrum and 8 images spanning from the visible to the near-infrared region – all onto a single metasurface.

What sets this innovation apart is not only its simplified design and fabrication process but also its enhanced image quality. The team tackled previous issues of image crosstalk and background noise by incorporating a noise suppression algorithm, resulting in clearer images with minimal interference between channels.

“This is the first demonstration of multiplexing spin and wavelength information through a single phase-optimization process while achieving low noise and high image fidelity,” said Professor Rho. “Given its scalability and commercial viability, this technology holds strong potential for a wide range of optical applications, including high-capacity optical data storage, secure encryption systems, and multi-image display technologies.”

This research was supported by the POSCO Holdings N.EX.T Impact Program, as well as the Pioneer Program for Converging Technology of the National Research Foundation of Korea, funded by the Ministry of Science and ICT.

The researchers at Linköping University in Sweden have achieved a significant milestone in the development of controllable flat optics. By carefully placing nanostructures on a flat surface, they have improved the performance of optical metasurfaces made from conductive plastics. This breakthrough has far-reaching implications for various fields, including video holograms, invisibility materials, sensors, and biomedical imaging.

Traditional glass lenses are often curved to refract light in different ways. However, these lenses take up space and become impractical when miniaturized. Flat lenses, on the other hand, offer a promising alternative. They are made of metalenses, which form a rapidly growing field of research with great potential. Despite their limitations, metasurfaces have garnered significant attention due to their ability to control light using nanostructures placed in patterns on a flat surface.

“Metasurfaces work by placing nanostructures in patterns on a flat surface and becoming receivers for light,” explains Magnus Jonsson, professor of applied physics at Linköping University. “Each receiver captures the light in a certain way, allowing the light to be controlled as desired.”

However, one major challenge facing metasurface technology is the inability to adjust their function after manufacture. Researchers and industry have requested features such as turning metasurfaces on and off or dynamically changing the focal point of a metalens.

In 2019, Magnus Jonsson’s research group at the Laboratory of Organic Electronics showed that conductive plastics can crack this nut. They demonstrated that the plastic could function optically as a metal and be used as a material for antennas building a metasurface. The ability to oxidize and reduce allowed the nanoantennas to be switched on and off.

The same research team has now improved performance up to tenfold by precisely controlling the distance between the antennas, which helps each other through collective lattice resonance. This advancement enables conductive polymer-based metasurfaces to provide sufficiently high performance for practical applications.

While the researchers have successfully manufactured controllable antennas from conducting polymers for infrared light, their next step is to develop the material to be functional in the visible light spectrum as well.

This breakthrough has significant implications for various fields and opens up new possibilities for innovation. As research continues to push the boundaries of metasurface technology, we can expect to see exciting developments in video holograms, invisibility materials, sensors, and biomedical imaging equipment.

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Revolutionizing Night Vision: Infrared Contact Lenses Unlock Human Potential

Imagine being able to see in complete darkness, not just with your eyes open but even when they’re closed. Sounds like science fiction? Think again. Neuroscientists and materials scientists have made this possibility a reality by creating contact lenses that enable infrared vision in both humans and mice.

The technology uses nanoparticles that absorb infrared light and convert it into wavelengths visible to mammalian eyes. This allows wearers to perceive multiple infrared wavelengths simultaneously, with infrared vision enhanced when participants had their eyes closed. Unlike traditional night vision goggles, these contact lenses don’t require a power source, making them non-invasive and wearable.

“Our research opens up the potential for non-invasive wearable devices to give people super-vision,” says senior author Tian Xue, a neuroscientist at the University of Science and Technology of China. “There are many potential applications right away for this material.”

For instance, flickering infrared light could be used to transmit information in security settings, rescue operations, encryption, or anti-counterfeiting scenarios.

The team combined nanoparticles with flexible, non-toxic polymers used in standard soft contact lenses. After ensuring the contact lenses were non-toxic, they tested their function in both humans and mice.

In human trials, participants wearing the infrared contact lenses accurately detected flashing morse code-like signals and perceived the direction of incoming infrared light. “It’s totally clear cut: without the contact lenses, the subject cannot see anything, but when they put them on, they can clearly see the flickering of the infrared light,” said Xue.

Additional tweaks to the contact lenses allow users to differentiate between different spectra of infrared light by engineering the nanoparticles to color-code different wavelengths. This technology could make the invisible visible for people with color vision deficiency (color blindness) and help them detect wavelengths that would otherwise be undetectable.

The researchers have also developed a wearable glass system using the same nanoparticle technology, enabling participants to perceive higher-resolution infrared information. Currently, the contact lenses can only detect infrared radiation projected from an LED light source, but the team is working to increase the nanoparticles’ sensitivity so they can detect lower levels of infrared light.

“In the future, by working together with materials scientists and optical experts, we hope to make a contact lens with more precise spatial resolution and higher sensitivity,” says Xue. This breakthrough has far-reaching implications for various fields, from healthcare to national security and beyond.