Scientists at Singapore’s Nanyang Technological University (NTU Singapore) have discovered a much easier way to generate unusual optical structures known as optical skyrmions by reviving a classic optical experiment that dates back more than 200 years.
Optical skyrmions are small, stable spiral patterns formed in the nature of light. Its structure is often likened to a hedgehog’s spine. Because they have the potential to encode and store information, researchers believe they are promising building blocks for future data storage, communication, and computing technologies.
Rather than relying on the expensive, highly engineered metamaterials traditionally required to produce optical skyrmions, the NTU team created them by shining a laser onto small circular disks. This approach provides a much easier way to generate, study, and control these complex optical structures.
The survey results were published in a magazine opticalled by Nanyang Assistant Professor Shen Yijie from NTU’s School of Science and Mathematics and School of Electrical and Electronic Engineering.
“What is remarkable is that optical skyrmions can be generated using the simple effect of light bending around an object, without relying on expensive and complex artificial metamaterials or highly specialized techniques,” explained Associate Professor Shen.
“This could make optical skyrmions more accessible to researchers. By lowering the technical barrier to creating and studying optical skyrmions, this method opens new possibilities for scientists to study how they can be used in future optics, materials and computing research.”
A classic light phenomenon finds new purpose
This breakthrough is based on the Poisson spot, a well-known optical phenomenon in which a bright spot appears at the center of the shadow cast by a circular object when illuminated by a coherent light source such as a laser.
Poisson’s point played an important role in early 19th century debates over the nature of light. At the time, scientists wondered whether light traveled only in straight lines as particles, or whether it behaved as waves that curved and spread out.
Wave theory predicted that a bright spot should appear at the center of the disk’s shadow, but otherwise complete darkness would be expected. Observations of Poisson spots have provided convincing evidence that light undergoes diffraction, that is, it bends and spreads as it passes around objects or through small apertures.
Four types of optical skyrmions at once
The researchers also found that the Poisson spot setup naturally generated up to four related topological field patterns simultaneously.
These include spin skyrmions, Stokes skyrmions, electric field skyrmions, and magnetic field skyrmions. Spin refers to properties such as rotation of light, while Stokes parameters describe polarization, or the direction in which a light wave oscillates as it travels.
Producing these four types together could give scientists a unique opportunity to compare how different optical skyrmions form, evolve, and interact within the same light field.
In the computer simulation, the structure is shown as an array of swirling arrows, showing how different properties of light change direction across the Poisson spot.
A simple way to control complex lights
Light has many properties that researchers can manipulate, including intensity, phase, polarization, spin, electric field vector, and magnetic field vector.
These properties can be arranged into topological structures, which are stable patterns even when stretched or distorted. By adjusting the conditions that form the light field, scientists may be able to precisely control the size, shape, and behavior of optical skyrmions.
“In the light spot we created, several types of light vectors can form a topological structure at the same time. These different light components are closely related, but they do not necessarily form the same topological pattern,” said Shen.
“Being able to generate and compare multiple skyrmions within one system could help researchers discover new relationships between the electrical, magnetic, and other physical properties of light.”
Potential applications in computing and photonics
Skyrmions were first proposed in particle and nuclear physics and have since become an important research area in condensed matter physics and magnetic materials. More recently, scientists have begun investigating optical skyrmions as stable particle-like structures that exist within light fields.
Previous methods to produce optical skyrmions relied on metamaterials, artificially engineered microstructures designed to manipulate light in ways not possible with traditional materials.
By replacing these complex systems with much simpler optical setups, the NTU team’s work could make optical skyrmion research more accessible. The discovery also provides the basis for future research in topological light, which could contribute to advances in photonics, advanced materials, information processing, and next-generation computing.
