ITMO shows a simple way to rebuild the topological states of light

(ORDO NEWS) — A group of scientists from ITMO, Australian National and Jilin Universities have developed a topological structure that allows you to dynamically rearrange the edge states of light.

Due to the special shape of the particles that make up the system, it is possible to change its properties by rotating individual particles.

The researchers demonstrated the effectiveness of such a solution during a microwave experiment. The results obtained will accelerate the development of topologically protected electromagnetic devices.

The idea of ​​replacing electronic devices with photonic devices, in which information is transmitted using light, is becoming increasingly popular.

In this regard, the concept of topological (edge) states of light is promising, which can propagate without scattering on defects and inhomogeneities or form localized states with a frequency resistant to various interferences from the external environment.

To obtain these states, it is necessary to use structures based on resonant particles arranged in a certain lattice. Usually, researchers select special design geometry, for example, changing the distance between particles. But such structures are difficult to regulate, especially in real time.

Scientists from the frontier laboratory “Investigation of fundamental physics using topological metamaterials” under the leadership of M.A. Gorlach of the New Physicotechnical Institute of ITMO University proposed to control the topological states of light by alternating the properties of the particles themselves, namely, their orientation.

This approach makes it possible not only to localize these states, but also to rebuild them much easier (to change the length of light localization, to “switch” the edge of the structure on which they appear).

The researchers demonstrated the effectiveness of the solution in a microwave experiment using a lattice of ceramic particles shaped like tiny horseshoes.

“By alternating particle orientations, stable protected edge states can be obtained. In addition, we can rotate these particles in real time, which allows us to dynamically rebuild the length of the localization of these states, switch the edge that will glow.

This turns out to be promising not only in microwaves, where our experiment was carried out, but also in the optical range,” says Daniil Bobylev, author of the study, PhD student at the New Physicotechnical Institute at ITMO University.

First, the scientists optimized the shape of a single particle. Then they made a one-dimensional array of such “horseshoes” (a system of coaxial asymmetric cylinders), which during the experiment is illuminated by microwaves of a certain frequency, demonstrating the distribution of the electromagnetic field.

“When we turned the ceramic discs, we saw that the localization changed from concentrated (in the center) to completely blurred if we changed the non-trivial structure to the trivial one.

This confirmed the results of theoretical conclusions and numerical simulations that we have demonstrated in previous works. This opens up great possibilities

“This work is one of the promising areas of work of the recently created laboratory “Investigation of fundamental physics using topological metamaterials”.

The possibility of flexible restructuring of the properties of a metamaterial is also important for us in another context, in the search for dark matter using resonators based on a medium of wires.

As a next step, we plan to generalize our results to the two-dimensional case,” says Maksim Gorlach, Head of the Frontier Laboratory, Senior Researcher at ITMO. The study was selected for publication on the cover of an issue of ACS Photonics.

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