Terahertz-Electronics with Particular Reference to Security Applications

Abstract

Electromagnetic signals at Terahertz frequencies have the advantage that their photon energies are in the low milli-electronvolt range and therefore not capable of breaking up organic molecules of living cells. Therefore they have been considered for many applications such as airport surveillance. These scanners can detect metals such as those of weapons hidden under clothing from a distance of several meters, without exposing the persons to harmful radiation. THz spectroscopy is used to characterize many materials, including packaging, explosives and drugs. A recent application has been to characterize single-wall nanotube thin film electrodes. In another approach, using a separate pump beam to excite charge carriers in a material shortly before the THz analysis is carried out, information about ultrafast carrier dynamics may be obtained. A recent example of such time-resolved THz measurement deals with poly (3-hexylthiophene) and methanofullerene blended films.