What Are Electromagnetic Metamaterials?

Electromagnetic metamaterials are compounds engineered to have unique structural as well as chemical properties that are not natural to the materials themselves. Nanoscale surfaces are created that can affect the metamaterial's reaction to ordinary light, as well as other types of radiation such as microwave radiation by the fact that the structural features are smaller in size than the actual wavelength of radiation. Properties such electromagnetic metamaterials are often created to display include unique dielectric effects, as well as a negative refractive index with silver metamaterials, which could be used to make a superlens that could resolve features a few nanometers in size or be used to view the interior of non-magnetic objects.

While electromagnetic metamaterials have a wide range of potential applications, the focus of much of the research into such materials as of 2011 has been in microwave engineering for advanced antennas and other magnetic-related systems. These artificially-structured materials are capable of developing magnetism features in the presence of microwave fields or terahertz-infrared fields that exist directly between the microwave and visible light range of the electromagnetic (EM) spectrum. Such materials would otherwise be non-magnetic, and stimulating this property in them is referred to in physics as creating Left Handed (LH) behavior. Creating such a behavior in non-magnetic devices would be instrumental in the manufacture of advanced filters and beam-shifting or phase-shifting electronics.

The uses of metamaterials would further miniaturize electronics components, as well as make circuits and antennas more selectively receptive or impervious to various bands of the EM range. An example of one application for a finer level of control over electromagnetic waves would be in global positioning system (GPS) technology that could transmit or block a more precise positioning signal than is currently possible in military targeting and jamming environments. This enhanced ability is made possible by the fact that electromagnetic metamaterials are an artificially-structured material form that both interacts with and controls ambient electromagnetic waves, making the materials both transmitters and receivers.

The types of metamaterials that demonstrate these properties have structural features engineered at the scale of the angstrom, or at a size of about one-tenth of a nanometer. This requires joint efforts by several fields of science to build such materials, including physics, chemistry, and engineering in nanotechnology and materials science. Gold, silver, and copper metals, as well as plasmas and photonic crystals are materials that have been used in constructing such electromagnetic metamaterials, and, as the science progresses, uses of metamaterials finds increasing applications in the field of optics. It is theorized that eventually a form of electromagnetic invisibility field could be generated by such metamaterials, where visible light could be bent around them to conceal their presence.