2023-07-11 22:00:00
Left-handed materials, or left-handed materials, are metamaterials. The name metamaterial dates from the end of the 1990s and corresponds to different classes of artificial materials in electromagnetism, optics, mechanics, heat, etc.
In the 1960s, Victor Veselago had studied the theoretical properties of an electromagnetic material exhibiting simultaneously negative permittivity and permeability. This is not found in natural materials. V. Veselago showed that the electromagnetic waves might propagate in such a material, and that in addition this one presented a negative optical index. However, he failed to realize it practically and it was not until 1999 and two articles by John B. Pendry that these materials were finally feasible in practice. Credit then goes to David R. Smith for combining the two concepts into a single negative-index material, first tested experimentally in 2000.
This early work in microwaves, and the amazing properties of left-hand materials, sparked the interest of researchers around the world. A flowering of publications followed, in microwaves, as well as in terahertz and optics. In this last area, the technological stakes are high since we have gone so far as to predict the birth of new optics, where the resolution of lenses and optical instruments would no longer be limited by diffraction. This prediction has since been tempered, and its realization remains dependent on advances in nanotechnology.
Examples of metamaterials operating at terahertz, infrared and visible wavelengths have been proposed. Even if they can still be improved, they show that in a short time extremely efficient devices have been produced and tested. This is all the more remarkable since, in these periodic structures, the elementary cell must have a characteristic size of the order of a tenth of the wavelength. This means that, in the visible, the cell has a typical dimension of 50 nm, with details of the order of a few nanometers. We are therefore in the field of nanotechnology, and there are few laboratories capable of producing this type of structure.
In microwaves, the issue is different. Applications in telecommunications and electromagnetic compatibility dominate, with different approaches and greater creativity, because the technological constraints are less stringent. Studies very quickly focused on the development of applications in the field of filters, phase shifters, antennas and materials for electromagnetic compatibility, with a systematic comparison to existing technologies and very high performance requirements.
This article presents in its first part the particular electromagnetic properties of these left-handed materials (MMG). In the second part, the methods of fabrication and characterization of these materials are detailed according to the frequency domains in which these materials are made. We will see that these methods are very different depending on whether we are using microwaves or optics. In the third part, concepts of one- and two-dimensional materials with a negative index are introduced. Finally, in the fourth part, components in free space are presented with their particular application to the characterization of these materials. The conclusion presents the perspectives of development and applications of these materials in the future.
1689472246
#Electromagnetism #lefthand #materials #Complete #file
