Light can now be made to rotate in a chosen direction without designing entirely new chiral molecules, according to researchers at the Korea Advanced Institute of Science and Technology (KAIST). By arranging ordinary, mirror-symmetric liquid-crystal molecules into microscopic pinwheel patterns, the team created structures capable of controlling whether emitted circularly polarized light rotates clockwise or counterclockwise. The approach could offer a simpler route to optical components for advanced displays, augmented- and virtual-reality devices, communications systems, polarization sensors, and anti-counterfeiting technologies.
Circularly polarized light is a specialized form of light whose electric field rotates as the wave travels. That rotation can be either left-handed or right-handed, and the distinction is useful because the two states can carry separate channels of information. Conventional technologies often require chiral molecules—molecules whose mirror images cannot be superimposed—to generate or manipulate this type of light. Creating such molecules, however, can involve complicated chemical synthesis, while mixtures of opposite-handed structures can cancel one another’s optical effects.
The KAIST team, led by Professor Dong Ki Yoon of the Department of Chemistry, developed a different strategy based on controlling molecular organization rather than molecular asymmetry. The researchers worked with achiral, rod-shaped liquid-crystal molecules that are individually symmetric. Under carefully controlled conditions, these molecules were confined within microscale spaces and encouraged to assemble into pinwheel-shaped structures. Although the molecules themselves had no inherent handedness, their collective arrangement could adopt either a clockwise or counterclockwise configuration.
The principle resembles the way a flat sheet of paper can be folded into pinwheels that turn in opposite directions. The paper remains the same, but the arrangement of its folds determines the final handedness. In a similar way, the liquid-crystal molecules used in the study were chemically unchanged, while the geometry of their assembly generated a chiral structure. This distinction is important because it separates the origin of the optical response from the chemical identity of the material itself.
The researchers first induced the molecules to self-assemble into microscopic pinwheels. A major challenge was preventing both handednesses from forming at the same time. If clockwise and counterclockwise structures appear in equal or nearly equal numbers, their optical responses can weaken or cancel, making it difficult to produce a strong, uniform signal across a large area. To solve this problem, the team introduced a chiral additive in a concentration of less than 1 percent of the total material. Rather than acting as the primary optical material, the additive served as a molecular guide that selected one pinwheel orientation.
This small amount of chiral material was sufficient to bias the self-assembly process and align the pinwheels with a common handedness. The result was a large-area array of microscale structures with a consistent orientation. The researchers then permanently transferred or replicated the arrangement onto polymer nanofibers, creating a stable chiral platform that could be used as a surface for other optical materials. This replication step is particularly significant because it suggests that the pinwheel architecture can be integrated into flexible or nanoscale devices rather than remaining limited to a temporary liquid-crystal state.
To test whether the structure could control light, the team coated the patterned platform with a conventional luminescent material. When excited, the luminescent coating emitted circularly polarized light. Crucially, the direction of that polarization was determined by the handedness of the underlying pinwheel array rather than by a change in the light-emitting substance. Reversing the orientation of the pinwheels switched the emitted light from one rotational direction to the other, demonstrating that the optical function originated from structural organization.
The finding illustrates a broader design principle in materials science: a material’s properties can emerge from how its building blocks are arranged, even when those building blocks lack the desired property individually. The same idea appears in photonic crystals, metamaterials, liquid-crystal devices, and biological structures, where nanoscale geometry can determine how light, sound, or electrons move. In this case, the pinwheel array creates a chiral optical environment that influences the interaction between the luminescent coating and the emitted electromagnetic field. The structure effectively transfers handedness to light without requiring a fully chiral emitter.
According to the researchers, the platform could help simplify the development of optical technologies that rely on polarization. Displays might use structurally controlled circularly polarized emission to improve light management and reduce optical losses. In augmented- and virtual-reality systems, chiral structures could be incorporated into lightweight polarization-control elements. Optical communication systems could potentially use left- and right-handed polarization states as distinct information channels, while security labels could exploit the ability of a patterned surface to produce a recognizable polarization signature. Polarization sensors may also benefit from materials whose response can be tuned through geometry rather than chemical redesign.
The study was led by first author Jeong Yeon Han, a Ph.D. candidate, in collaboration with scientists from Chungnam National University, Ajou University, Yonsei University, and Japan’s RIKEN. Han explained that conventional methods often produce left- and right-handed structures together, reducing the overall chiral response. By designing the additive concentration and assembly conditions so that one orientation was selected across a broad area, the team overcame that limitation. Professor Yoon said the work demonstrates a new optical-materials principle in which the rotation direction of light is controlled by molecular arrangement rather than by the complex chemical structure of chiral molecules.
Published in Nature Communications, the study presents the pinwheel array as a route to scalable chiral optical materials based on widely available achiral components. The researchers’ next challenge will be to refine the uniformity, efficiency, and manufacturing compatibility of the structures and to determine how they perform in practical devices. If those obstacles can be addressed, microscopic pinwheels made from ordinary molecules could become a powerful way to program the behavior of light—turning molecular architecture into an optical control switch.
Subject of Research: Structural control of circularly polarized light using microscale chiral pinwheel arrays formed from achiral liquid-crystal molecules.
Article Title: Microchiral pinwheel arrays based on achiral molecules
News Publication Date: 14-Aug-2026
Web References: https://doi.org/10.1038/s41467-026-76089-z
References: Han, Jeong Yeon, et al. “Microchiral pinwheel arrays based on achiral molecules.” Nature Communications. DOI: 10.1038/s41467-026-76089-z.
Image Credits: KAIST
Keywords
Circularly polarized light, chirality, achiral molecules, liquid crystals, pinwheel structures, optical materials, nanofibers, photonics, displays, optical communications, polarization sensors, metamaterials, KAIST
Tags: advanced optical communication systemsanti-counterfeiting optical methodschiral molecule alternativescircularly polarized light controlliquid crystal molecular organizationliquid crystal pinwheel patternsmolecular arrangement in photonicsoptical device innovationpolarization sensors technologypolarized light in displayssimplifying polarized light generationvirtual reality optical components
