Scientists at Singapore’s Nanyang Technological University (NTU Singapore) have made a groundbreaking discovery in generating unique optical structures called optical skyrmions by reviving a classic optical experiment over 200 years old.
Optical skyrmions are compact, stable spiral patterns in light, often likened to the spine of a hedgehog. Their ability to encode and store information positions them as promising candidates for next-generation data storage, communication, and computing technologies.
Instead of using costly, engineered metamaterials typically needed to produce optical skyrmions, the NTU team developed a more straightforward method by shining a laser on small circular disks. This innovative approach simplifies the generation, study, and control of these complex optical structures, making it more efficient.
The research findings were published in the journal Optica, led by Nanyang Assistant Professor Shen Yijie from NTU’s School of Science and Mathematics and School of Electrical and Electronic Engineering.
“What’s remarkable is that optical skyrmions can be generated using the simple phenomenon of light bending around an object, eliminating the need for expensive, complex metamaterials,” explained Associate Professor Shen.
“This accessibility could lower the technical barriers to studying optical skyrmions, unlocking new possibilities for scientists to explore their applications in optics, materials, and computing research.”
A Classic Light Phenomenon Finds New Purpose
This breakthrough hinges on the Poisson spot, a well-documented optical phenomenon where a bright spot appears at the center of a shadow cast by a circular object illuminated by a coherent light source, such as a laser.
Historically, Poisson’s point played a crucial role in early 19th-century debates about the nature of light, probing whether it traveled in straight lines like particles or behaved as waves that bend and spread.
Wave theory anticipated a bright spot at the center of the disk’s shadow, with complete darkness elsewhere. Observing Poisson spots provided compelling evidence that light undergoes diffraction, bending and spreading as it navigates around objects or through narrow apertures.
Generating Four Types of Optical Skyrmions Simultaneously
The researchers discovered that the Poisson spot setup could naturally yield up to four correlated topological field patterns at once.
These patterns include spin skyrmions, Stokes skyrmions, electric field skyrmions, and magnetic field skyrmions. Here, ‘spin’ pertains to light rotation properties, while Stokes parameters describe polarization, indicating the oscillation direction of a light wave.
Simultaneously generating these four types provides scientists with a unique opportunity to compare how different optical skyrmions form, evolve, and interact within a single light field.
In computer simulations, the structure manifests as an array of swirling arrows, demonstrating how various light properties shift direction across the Poisson spot.
A Simple Method to Control Complex Light
Researchers can manipulate various properties of light, including intensity, phase, polarization, spin, electric field vector, and magnetic field vector.
These properties can be organized into topological structures—stable patterns that remain unchanged even when stretched or distorted. By fine-tuning the conditions that create the light field, scientists may gain precise control over the size, shape, and behavior of optical skyrmions.
“In the light spot we created, multiple light vectors can form a topological structure concurrently. Although these different light components are interconnected, they do not always produce identical topological patterns,” Shen noted.
“Being able to generate and analyze multiple skyrmions within a single system could aid researchers in discovering new relationships between the electrical, magnetic, and other physical properties of light.”
Potential Applications in Computing and Photonics
Skyrmions originated in particle and nuclear physics and have evolved into a significant area of research within condensed matter physics and magnetic materials. Recently, scientists have begun investigating optical skyrmions as stable particle-like structures existing within light fields.
Traditional methods to generate optical skyrmions relied on metamaterials—artificially engineered microstructures designed to manipulate light in ways unattainable with standard materials.
By substituting these complex systems with simpler optical setups, the NTU team’s work could render optical skyrmion research more accessible. This discovery lays the groundwork for future explorations in topological light, potentially paving the way for innovations in photonics, advanced materials, information processing, and next-generation computing.
Source: www.sciencedaily.com