Electromagnetism of Left-handed Material

Left-handed materials are known as metamaterials. The term metamaterial dates back to the late 1990s and refers to various classes of artificial materials used in electromagnetics, optics, mechanics, thermics, etc.

In the 1960s, Victor Veselago studied the theoretical properties of an electromagnetic material with simultaneous negative permittivity and permeability. This does not occur in natural materials. V. Veselago showed that electromagnetic waves could propagate in such a material, and that it also had a negative optical index. However, he failed to realize this in practice, and it wasn't until 1999, with two papers by John B. Pendry, that such materials finally became feasible in practice. David R. Smith is then credited with combining the two concepts in a single negative-index material, tested experimentally for the first time in 2000.

This early work in microwaves, and the astonishing properties of the left-hand materials, aroused the interest of researchers all over the world. A flurry of publications followed, in microwaves, terahertz and optics. In the latter field, the technological stakes are high, with predictions of the birth of a new kind of optics, in which 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 were presented. Although there is still room for improvement, they show that in a short space of time, extremely high-performance devices have been produced and tested. This is all the more remarkable given that, 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 range, the cell has a typical size of 50 nm, with details of the order of a few nanometers. We are therefore in the field of nanotechnology, and there are very few laboratories capable of producing this type of structure.

In microwaves, the stakes are different. Applications in telecommunications and electromagnetic compatibility dominate, with different approaches and greater creativity, as technological constraints are less stringent. Studies quickly focused on the development of applications in the field of filters, phase shifters, antennas and materials for electromagnetic compatibility, with systematic comparison to existing technologies and very high performance requirements.

The first part of this article describes the special electromagnetic properties of these left-hand materials (LHMs). In the second part, the methods used to manufacture and characterize these materials...