In 1818, the French Academy of Sciences held a competition to settle one of the great scientific debates of the era: was light made of particles or waves? A young physicist named Augustin-Jean Fresnel submitted a wave theory of diffraction. Siméon Denis Poisson, a particle-theory supporter, pointed out what he thought was an absurd consequence: if Fresnel was right, a bright spot should appear in the center of the shadow of a round object — a spot that should not exist under particle theory. When the experiment was performed, the bright spot appeared exactly as predicted. The "Poisson spot" became a landmark proof of the wave nature of light, and Fresnel won the competition.
Fast-forward to 2026. Researchers at Nanyang Technological University in Singapore have discovered that the same Poisson spot provides a remarkably simple way to generate optical skyrmions — topologically protected swirls of light whose structure is incredibly stable against disturbances. Until now, creating these exotic light patterns required complex metamaterials and expensive nanofabrication. The NTU team, led by Assistant Professor Shen Yijie, showed that a basic circular obstacle, a laser beam, and a camera are enough to produce stable skyrmions in light. The results were published in the journal Optica.
Optical skyrmions are the photonic equivalent of magnetic skyrmions, which are already studied for next-generation data storage. In a magnetic skyrmion, the magnetization direction twists into a knot-like configuration that is extremely stable — it takes very little energy to shift them, but they resist being erased. Optical skyrmions bring this same property to light. Because they are topological structures, they can encode information in a way that is highly resistant to noise and scattering. This makes them promising for ultra-dense data storage, all-optical computing, and secure communications where information is carried by the light's structure rather than its intensity.
What makes the NTU discovery particularly significant is its simplicity. The team used a 5-millimeter metal disk placed in a laser beam — essentially the same setup as the 1818 experiment — and observed that the resulting Poisson spot naturally forms a skyrmion texture. By varying the distance from the disk and the polarization of the input light, they could control the skyrmion's size and orientation. The approach requires no specialized fabrication, which means it can be reproduced in any optics lab and potentially scaled for practical applications.
Knowledge takeaway: The 200-year-old Poisson spot — a bright dot of light at the center of a shadow — can naturally generate optical skyrmions, swirling light structures that are topologically protected and could enable ultra-dense data storage and all-optical computing without complex nanofabrication.