Scientists have solved a decades-old mystery about whether light can be effectively trapped in a 3D forest of microscopic particles.
Using a new method for crunching huge amounts into a model of particle interactions, a team of physicists in the US and France has revealed the conditions under which a burst of light can be stopped by defects in the right kind of material.
known as Anderson localizationFollowing the American theoretical physicist Philip W. Anderson, electrons can become trapped (localised) in disordered materials with randomly distributed distortions. His proposal in 1958 was an important moment in contemporary condensed matter physics, as it was applied across quantum mechanics as well as classical mechanics.
Where in the classical world we imagine a point-like particle simply bouncing like a pinball through a maze as it gets scattered by defects, the wave-like quantum identity of the particle gets more and more chaotic, forcing the electron to stop and spin matter into an insulator.
Something similar seems to happen because electromagnetic waves shape light through some materials, at least in one or two dimensions. Until now, no one has been able to tell if physics sticks to three dimensions (not through Lack of trying).
Finally, advances in numerical computation and simulation software have solved the puzzle.
“We haven’t been able to simulate large 3D systems because we don’t have enough computing power and memory,” he said. He says Applied physicist and electrical engineer Hui Cao, of Yale University in Connecticut.
“People have been experimenting with different numerical methods. But it was not possible to simulate such a large system to show whether or not there is localization.”
using a new tool called FDTD Tidy3D softwareCao and her colleagues were able to perform calculations that would normally take days in just 30 minutes, which speeds up the simulation process. The tool uses an improved version of The time domain with finite differences (FDTD) algorithm, which divides spaces into grids and solves equations at each grid point.
The software also made it possible to test different system configurations, sizes, and architecture parameters. The results of the numerical simulations obtained by the researchers showed that they were free of artifacts that were a problem in the Previous studies.
What the researchers found is that light cannot be localized in 3D in dielectric (insulating) materials such as glass or silicon, which may explain why scientists have been baffled for so long. However, there was clear numerical evidence of 3D Anderson localization in random packings of conductive metallic domains.
“When we saw Anderson localization in the numerical simulation, we were thrilled,” He says cao. “It was incredible, considering that there had been such a long pursuit by the scientific community.”
The results give scientists a better idea of where to direct their research in the future, and a greater understanding of how Anderson 3D localization may occur in different types of materials.
Part of this research effort will seek to observe the effect experimentally, evidence that has so far remained “stubbornly elusive” to scientists. Tsao and colleagues proposed one possible experiment they say They will avoid the pitfalls of previous experimental work, which they hope will “provide a telltale sign of Anderson localization.”
Furthermore, some areas where the discovery may be important include the development of optical sensors, and the construction of energy conversion and storage systems. Right now, we know Anderson localization can work in three dimensions, some 65 years after it was first imagined.
“Three-dimensional confinement of light in porous metals can enhance optical nonlinearity, photonic-matter interactions, random laser control as well as targeted energy deposition,” He says cao. “So we expect there to be a lot of applications.”
Research published in nature physics.