Electromagnetical and Optical Metamaterials

Metamaterials, as their name suggests, are artificial materials with physical properties superior to those of natural materials. "Meta" is a Greek prefix meaning "beyond" or "a level above", as in metaphysical or metalogical.

Metamaterials are therefore materials with properties "beyond" what we can expect to observe in natural materials. This concept can be applied to all areas of physics. More specifically, in electromagnetism and optics, metamaterials present new properties likely to excite the imagination of researchers and engineers, such as a negative optical index or an inverted Doppler effect, for example. But we'll see later that a metamaterial doesn't always have a negative optical index. It may have only negative permittivity or permeability. It may only be magnetic, but at optical frequencies. It can also have an optical index of zero. But we'll also see that the concept of metamaterial is actually a very old one, since the first metamaterials were colored optical glasses found in Roman times, and in cathedrals where they were used to create magnificent stained-glass windows.