Researchers from Tel Aviv University and Rafael have succeeded for the first time in measuring a periodic structure of conducting loops in the form of topological bonds – a development that could revolutionize optics, communications, and computing.
The ability to precisely design and control the propagation, refraction, and polarization of light and radio waves is a cornerstone of our ability to transmit and receive signals, and acquire information from the environment. Thin metasurfaces that enable this control are an important pillar in the development of innovative technologies such as compact antennas, advanced sensors, and flat lenses. In the future, metasurfaces are expected to lead to revolutions in areas such as high-speed communications (5G, 6G), medical devices, active camouflage, and optical computing thanks to their flexibility and ability to be integrated into complex systems while saving space and energy.
A new study by Tel Aviv University and Rafael presents an innovative approach to the construction and design of unique surfaces in which there is a close connection between the electric and magnetic currents generated in the structure. As part of the study, the researchers succeeded for the first time in creating a cyclic structure based on wires in the form of topological knots and also in measuring it, thereby confirming the theoretical predictions regarding the behavior of these structures.
The researchers explain that the importance of the study is that it establishes a connection between simple properties of the structure (topological properties) and the expected response to electromagnetic waves that affect the structure, and allows for simple design principles that hardly require complex calculations.
The research was conducted under the leadership of Nadav Goshen, a research student at Tel Aviv University, under the supervision of Dr. Yarden Mazor from the School of Electrical and Computer Engineering at Tel Aviv University. The research was funded in part by the Academic Collaboration Research Fund of the Research and Development Division at Rafael. The research findings were recently published in the prestigious journal Science Advances.
In the paper, the research team explains that metasurfaces are two-dimensional or three-dimensional structures composed of a periodic array of unit cells smaller than the wavelength. In our case, the unit cells (which repeat in a periodic, two-dimensional manner) consist of wire loops that form small particles in the form of toroidal knots (diagram, left), i.e. wires defined on the surface of an imaginary ring, and "wrapped" around it several times.
These particles have a chiral structure – they are not identical to their mirror images (like the palms of our hands). This special structure allows the electrical and magnetic responses of each particle to be coupled, thus also affecting the overall behavior of the metasurface (diagram, right. Surface created using NanoDimension’s integrated printing technology).
Dr. Mazor: To demonstrate the performance of the metasurface, we chose a specific wire from the knots family (the wire in the diagram on the left is called Trefoil) that we produced using 3D printing that combines an electrically conductive metal (silver) for the wire itself, and an insulating plastic material that provides mechanical strength and binds the periodic structure. In the Trefoil-based metasurface, we showed that a high level of control over the polarization properties of the wave transmitted from the surface as a function of frequency is possible, while almost completely preventing the reflection of the incident waves. This control was demonstrated through measurement and comparison with numerical simulation. In addition, we presented a "flat" version using printed circuit board (PCB) manufacturing technology of a particle with identical topological characteristics, and we showed that the basic effect is preserved, despite the change in the specific geometry, a fact that establishes the properties of the particle as derived from its topological characteristics. Despite the geometric simplification.
Dr. Yehudit Hocherman-Fromer, Senior Vice President of R&D at Rafael: "The close collaboration between academia and industry is essential for leading true innovation and technological superiority. At Rafael, we see great value in a deep connection with research institutions - not only as a mutual enrichment, but as a basis for the growth of groundbreaking ideas and their transformation into practical solutions in the field. The long-standing collaboration with Tel Aviv University is an excellent example of this - a combination of research excellence with the challenges of the operational world, allowing us to build tomorrow's security technologies today."
In conclusion, the researchers note that one of the main contributions of the study is obtaining a single-layer structure that implements the electric-magnetic coupling (instead of multilayer structures, as is usually the case to realize this coupling) and through simple design rules based on the properties of the particle. These findings open the door to advanced applications in the world of optics, quantum and millimeter-wave communications.
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One response
Say topology again and I'll jump out the window.
I guess they want to advertise success, without detailing what they want to achieve.