The study was jointly led by Dr. Jeong-Geun Yun, from Samsung Research, and Junsuk Rho, a professor at POSTECH. Hyunjung Kang, a researcher at POSTECH, served as co-first author. Samsung adopted a comprehensive approach — spanning ideation, implementation and validation — to demonstrate the potential of next-generation photonic device technologies and new opportunities for product differentiation.

In particular, the research shows promise for reducing the thickness and weight of extended reality (XR) devices and lowering the height of smartphone camera modules — offering a possible solution to the so-called “camera bump,” where the camera protrudes from the body of the device. Most notably, the team successfully overcame long-standing technical limitations that had hindered the commercialization of metalenses.

▲ (From left) Professor Junsuk Roh and researcher Hyunjung Kang, both from POSTECH, and Dr. Jeong-Geun Yun from Samsung Research

World’s First Implementation of Two-Third Wavelength Phase Delay

A metalens is an ultra-thin lens that manipulates light using nanostructures — much thinner than a human hair — arranged on a flat surface, rather than relying on curved surfaces like traditional lenses. This design makes metalenses ideal for developing compact and lightweight optical devices.

To control light precisely, a metalens must create a phase delay¹ of one wavelength — the distance light travels in one oscillation. This phase delay ensures light waves overlap properly at the focal point, producing a sharp image. Achieving this has typically required constructing tens of millions of extremely narrow and tall nanostructures with aspect ratios² of at least 1:10. These structures are difficult to fabricate and prone to breakage, posing a major challenge to commercialization.

▲ The operating principle of metalenses

“Metalenses have been difficult to commercialize due to complex fabrication and low mechanical stability. To overcome this, we collaborated with experts in design, simulation, manufacturing and validation to develop a new nanostructure design method.”

— Dr. Jeong-Geun Yun, Samsung Research

The team was the first in the world to propose a method of achieving light diffraction using a phase delay of only two-thirds of a wavelength, rather than the conventional full wavelength. This approach leverages the phenomenon that the nanostructures forming a supercell³ maintain a constant phase gradient even with a two-thirds wavelength phase delay, allowing the wavefront to remain stable in the far field.

Because phase delay is proportional to a nanostructure’s width and height, this method allowed the aspect ratio to be reduced to about 1:5. As a result, the nanostructure height was lowered without compromising optical performance. These improvements reduce fabrication difficulty and defect rates, improve structural stability and boost production and cost competitiveness.

▲ A metalens with reduced nanostructure height achieved aspect ratio adjustment

New Possibilities in Camera Optics

Using the newly developed metalens, the team built an ultra-compact infrared eye camera for XR devices. Despite its thin profile, the camera demonstrated accurate pupil tracking and iris pattern recognition.

By integrating the metalens, the team reduced the camera’s thickness by 20% compared with conventional refractive-lens cameras — from 2.0 millimeters to 1.6 millimeters — resulting in reduced weight and volume. The system also achieved precise gaze tracking and iris feature-point recognition at a wide 120-degree field of view. In addition, modulation transfer function (MTF) performance⁴ improved from 50% to 72%.

A New Pathway to Metalens Commercialization

This study introduces a new design principle for controlling light diffraction — reducing phase delay requirements for while unlocking the potential for high optical performance, mechanical stability and cost efficiency.

Looking ahead, the technology is expected to expand into the visible light spectrum and be applied to minimizing smartphone camera protrusion and miniaturizing a range of imaging sensor systems — paving the way for new forms of device differentiation.

Samsung will continue to pursue diverse research initiatives, including industry-academia collaborations, to secure next-generation technologies that help shape the future.

¹ A phenomenon in which a wave of a single frequency arrives later at another point due to a delay in its propagation
² The ratio of a nanostructure’s height to its width
³ The smallest structural unit that generates diffraction, formed by an arrangement of nanostructures
⁴ A measure of a lens’s ability to reproduce image sharpness

The paper, titled “Roll-to-plate printable RGB-achromatic metalens for wide-field-of-view holographic near-eye displays,” reflects the findings of research conducted by Samsung and POSTECH’s joint research team, wherein they developed an achromatic metalens free from color distortions and combined it with holographic displays to overcome various optical aberrations. This innovation paves the way for compact yet high-quality holographic XR wearable devices and applications in cameras and sensors.

Dr. Seokil Moon from Samsung Research and Professor Junsuk Rho from POSTECH led the study, with researchers Minseok Choi, Joohoon Kim and Kilsoo Shin from POSTECH also listed as co-authors of the paper.

Overcoming Conventional Chromatic Aberration Limitations To Achieve a Compact Achromatic Metalens

A metalens is a flat lens composed of nanoscale structures capable of controlling light diffraction, which can drastically reduce the size and thickness compared to traditional convex optical lenses.¹ For this reason, it has been recognized as a next-generation optical component for applications in displays and cameras, sparking over a decade of research.

Despite these advantages, metalenses have encountered technical challenges in product development due to severe chromatic aberration,² which leads to significant image distortion.

Previous efforts to eliminate chromatic aberration in metalenses relied on designing individual metastructures independently and subsequently assembling them onto a substrate. As a result, the interrelationships between structures were overlooked during the design phase, preventing the complete reduction of chromatic aberration in the final lens.

The research team overcame the challenge of chromatic aberration reduction by redefining the conventional design approach for metalenses. By accounting for the interrelationships between all metastructures during the design phase and designing them simultaneously, the team has successfully eliminated chromatic aberration after fabrication.

In addition to eliminating chromatic aberration, the achromatic metalens developed by the team also achieves a shorter focal length, significantly reducing the lens’ size and weight.³

Higher Resolution and Less Eye Strain With a Single Lens

Typically, metalenses exhibit various optical aberrations beyond chromatic aberration, with image distortion worsening as screen size increases. These issues have traditionally been addressed by combining multiple lenses. However, the research team has resolved various optical aberrations within the device by integrating a single achromatic metalens with a holographic display, achieving a wide field of view and distortion-free, high-quality images.

Additionally, through technical validation, the research team has demonstrated that substituting conventional optical lenses and displays with achromatic metalenses and holographic displays enables the delivery of compact, lightweight and virtual images that cause less eye strain.⁴

The findings of this study are anticipated to be applied to immersive media devices such as those equipped with extended reality (XR) capabilities. They will also be used in various optical systems — including displays, cameras and sensors — to enhance performance and reduce size.

Through this collaboration between industry and academia, Samsung has validated the entire process — from conceptualizing innovative ideas to implementation — confirming the potential for advancing various future optical systems and securing next-generation display technologies.

Samsung remains committed to ongoing research efforts, aiming to secure groundbreaking technologies that will shape the future through continued collaborations with academia and other industry-leading initiatives.

¹ A convex lens typically has a thickness of several millimeters, sometimes exceeding a centimeter, whereas metalenses are much thinner, usually less than 0.5 mm.
² Chromatic aberration, also called color fringing, occurs when a lens fails to focus all colors to the same point, creating colored fringes along the edges of objects in photographs.
³ Compared to previously proposed achromatic metalenses, this research has fabricated metalenses that are 3–5 times larger in size while maintaining the same focusing power (numerical aperture).
⁴ The image quality is enhanced by 13% after aberrations are corrected using the holographic display. The image quality is measured using the peak signal-to-noise ratio (PSNR), which is widely used in image and signal processing.