KAIST

<(From Left)Dr. Joonkyo Jung. Professor Jonghwa Shin>

A new type of hologram technology has been developed that uses the motion of light as a “key,” revealing information only under specific conditions. This is gaining attention as a novel approach that can simultaneously overcome the limitations of existing optical communication and security technologies.

KAIST (President Kwang Hyung Lee) announced on the 4th of May that a research team led by Professor Jonghwa Shin from the Department of Materials Science and Engineering has developed a next-generation vectorial hologram metasurface that uses the “total angular momentum (TAM)*” of light as a key for information selection, enabling the realization of different vectorial images depending on the state of the incident light.
 *Total Angular Momentum (TAM): a physical quantity that represents both the vibration direction (polarization) and rotational (twisting) properties of light, enabling the creation of precise vectorial images whose intensity and polarization distribution vary depending on the state of light

Previously, research utilizing either the vibration direction of light, known as “polarization,” or the property of light twisting in a helical form, known as “orbital angular momentum (OAM),” had been actively pursued. However, independently controlling these two properties within a single device had long been considered an unsolved challenge in the field of optics.

To address this, the research team precisely designed nanoscale structures much smaller than the thickness of a human hair and implemented a “bi-layer metasurface” by stacking them in two layers. A metasurface is an optical device based on ultra-fine artificial structures designed to freely control the direction and properties of light.

This device uses the “total angular momentum (TAM),” which combines the polarization and degree of twist of light, like a complex encryption key. In other words, the device responds and reconstructs hidden information only when light with a specific vibration pattern and a specific number of twists is incident. With this technology, even if light appears identical externally, the information cannot be read without the designated “light key,” ensuring high security.

<Conceptual Diagram of the Study>

In addition, the twisting state of light (OAM) can theoretically take on a very wide range of values, significantly increasing the amount of information that can be carried by a single light beam. This also enables expansion into ultra-high-capacity optical communication technologies capable of transmitting far more data simultaneously than before.

In particular, this study is meaningful in that it goes beyond simple intensity-only image implementation and achieves a “vectorial hologram” that precisely controls the vibration direction (polarization) of light at each point in the image. A vectorial hologram is a high-dimensional holographic technology that represents not only the intensity of light but also its vibration direction information.

<Vector hologram that generates independent intensity and polarization images depending on the conditions of the incident light>

This achievement is the first demonstration that two key properties of light—polarization and twist—which had been difficult to separate physically, can be independently controlled within a single device. This is expected to enable applications not only in next-generation display technologies such as immersive holograms, smart glasses, augmented reality (AR), and virtual reality (VR) devices, but also in various fields including anti-counterfeiting security labels and ultra-high-speed optical communication.

Professor Jonghwa Shin stated, “This study demonstrates that polarization and twist, which are fundamental properties of light, can be combined into a single independent information key and freely utilized,” adding, “It will evolve into a key platform for security systems that are difficult to replicate and for ultra-high-speed, ultra-high-capacity optical communication technologies.”

This study, with Dr. Joonkyo Jung as the first author, was published online on March 12 in the international journal Advanced Materials.
 ※ Paper title: “Arbitrary Total Angular Momentum Vectorial Holography Using Bi-Layer Metasurfaces,” DOI: 10.1002/adma.202519106

This research was supported by the Ministry of Science and ICT through the “Nano Materials Technology Development Program” and the “Group Research Support Program,” as well as by the Ministry of Trade.