A research paper titled “Compact eye camera with two-third wavelength phase-delay metalens” — focused on ultra-compact metalenses for eye cameras and conducted through a joint industry-academia project between Samsung Electronics and Pohang University of Science and Technology (POSTECH) — has been published in the internationally renowned academic journal Nature Communications.
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