AFRL-Funded Researchers Combine Terahertz Radiation and Metamaterial Technology to Detect Explosives Published Jan. 4, 2008 By Air Force Office of Scientific Research AFOSR Arlington, Va. -- AFRL-funded researchers from the University of Bath, England, have developed wire structures that combine terahertz (THz) radiation with metamaterial technology to provide a straightforward explosives detection capability. The metawires guide THz wavelengths into narrow spaces or holes, where hidden explosives or other flaws and impurities readily absorb the THz radiation and are detected as a result of this absorption. This combination of THz radiation and metamaterial technology is useful because it provides the Air Force a portable means for investigating materials suspected of having flaws, impurities, hidden compartments, or similar features visible through the use of THz radiation. Factors such as strong atmospheric absorption, coupled with a lack of compact sources, detectors, and associated components, have caused scientists to debate the usefulness of THz radiation, which occupies a region of the electromagnetic spectrum somewhere between long-wave infrared and microwave radiation. The researchers were able to accomplish this particular investigation by passing THz waves through a wire with periodic grooves cut along its length. The grooves cause the radiation to adhere closely to the wire. Theoretically, a grooved wire that is also tapered will concentrate the THz radiation at the wire's tip, creating an intense source of THz radiation for insertion inside other structures as a probe.