Physicists from the University of Warsaw have managed to trap beams of infrared light in a nanolattice made of atoms just 42 nanometers thick—about 2,000 times thinner than a human hair. The findings were published in the journal ACS Nano.
Material with a record-breaking refractive index
Infrared light has longer wavelengths than visible light—which is why it is physically difficult to confine it within a microscopic space. The trap must be smaller than the wavelength, which places strict demands on the material.
The key was a film of molybdenum diselenide (MoSe₂). This ultra-thin semiconductor has an exceptionally high refractive index (around 4.5), meaning it has the ability to slow down and “bend” light. It is precisely this property that allows photons to be confined within a volume significantly smaller than the wavelength in a vacuum. Although the compound has long been known to science, it had not previously been possible to produce it reliably at the nanoscale. The team grew an atomically thin film and used nanoprinting to create a periodic lattice within it. Its geometry is designed to overcome the diffraction limit—the barrier that typically prevents light from being compressed beyond its own wavelength. This configuration allows the radiation to be literally “trapped” inside the nanostructure.
Bound state in the continuum
In addition to the material, another physical effect was required—the so-called “bound state in the continuum” (BIC). This is a phenomenon in which light waves remain confined within a structure due to destructive interference, even though waves that “escape outward” are propagating nearby. For the BIC to work, the lattice must be precisely calculated and manufactured—the researchers carefully modeled the structure before building it physically.
What does this mean in practice?
This is a step toward creating computers that use light instead of electricity. Unlike modern PCs, which generate heat and lose energy due to the resistance of metals, photonic processors will process data at the speed of light. The ability to trap photons in traps just 42 nm thick demonstrates that such components could be even more compact than today’s microchips. Widespread adoption is still a long way off: the film-growing process itself is still imperfect—the team had to polish the material with silk cloths to achieve atomic-level smoothness and eliminate irregularities. However, the researchers are confident that the approach can be further developed and extended to other materials in the family of transition metal dichalcogenides (TMDs)—similar ultrathin structures with comparable properties.
According to sciencealert.com
