What chemical elements do the metamaterials consist of?

Answer

Dear Jan,

Metamaterials–as you probably know–are “man-made” materials that have very special physical properties not found in natural materials. In principle, these can be any physical properties, such as mechanical or thermal, for example, but as far as I know the term “metamaterials” is mainly used in photonics (the science and technology of light). So we specifically mean new materials with very special optical properties.

With these metamaterials you can do very special things with light, for example make an “invisibility cloak”, in which you can put an object, but where the light rays go around nicely (see for example http://uk.gizmodo.com/2006/10 /23/muggles_invent_invisibility_cl.html for a good illustration).

Ok, back to your question now. Ordinary materials are usually made up of the atoms listed in Mendeleev’s table. In metamaterials we are usually going to use electrical circuits as the basic unit; the light then interacts with the electrical circuits instead of atoms. See http://www.grc.nasa.gov/WWW/RT/2003/images/5620wilson-f4.jpg for a photo of such metamaterial. On this webpage you can see that the metamaterial is made of “printed circuit board” (these are a kind of plastic plates) on which circuits are written in a certain shape with copper.

It is of course true that the plastic and the metal used again consist of the “normal” atoms, in this case mainly carbon and hydrogen for the plastic and copper for the metal. Sometimes quartz (silicon+oxygen) or semiconductors are also used. But in a metamaterial there is a structure (the electrical circuits) arranged on a length scale that is larger than the atomic, but smaller than the wavelength of light. By this I mean that there are many atoms in one electrical circuit, but a metamaterial in itself consists of a large number of these circuits.

I hope this explanation can somewhat answer your question, otherwise you can certainly ask for more clarification.

Kind regards,

Philippe Tassin,
Free University of Brussels