The researchers showed that there are complex configurations of displacement currents inside the particle, which lead to toroidal moments of higher orders, and that the complex interaction of currents in a particle can switch it into a special nonradiative state. These results could lead to the development of more efficient devices.
Alexander Shalin, head of the International Scientific Laboratory Nano-Optomechanics of ITMO University, compared the science to a mechanism that can be adjusted to different modes of operation using different gears.
“A multipole is the same gear for a particle,” he said. “Particles of complex shape, as complex mechanisms, can perform more different tasks. But they have more gears, and due to lack of information about them, it was impossible to control the work of such particles earlier.”
Recently, dielectric nanoparticles have been actively used to control light at nanoscale. They behave better than previously proposed plasmon particles, avoid energy loss, and obtain interesting physical effects, meaning that dielectric particles can be used, for example, to create nanolasers, nanoantennas, sensors, or information transfer devices. Scientists are trying to study their behavior in detail to apply them effectively.
The research was published in Laser & Photonics Reviews (https://doi.org/10.1002/lpor.201800266).