Terahertz (THz) Wave Technology

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“Terahertz (THz) wave technology, has great potential for homeland security and military uses because it can "see through" clothing and packaging materials and can identify immediately the unique THz "fingerprints" of any hidden materials; a major breakthrough opens the way for detecting hidden explosives, chemical, biological agents, and illegal drugs from a distance of twenty meters” (Homeland Security Newswire).

What makes Terahertz so interesting and a huge breakthrough for the use of Homeland Security is that THz radiation transmits through just about everything that is not metal or a liquid. What is important is that every substance has its own THz fingerprint, which when combined with a database of banned substances, can set off red flags. It has no harmful threats to humans, which is another critical part of using this technology. However, problems still do exist. The first is the reason why it took so long to develop this technology, water vapor. According to Dr. Zhang, “the “all optical” technique for remote THz sensing uses laser induced fluorescence, essentially focusing two laser beams together into the air to remotely create plasma that interacts with a generated THz wave. The plasma fluorescence carries information from a target material to a detector where it is instantly compared with material spectrum in the THz “library,” making possible immediate identification of a target material.” Using the induced fluorescence fixes the problem of water vapor. Another issue is that this technology cannot see inside the body. So if somebody swallowed drugs or explosives, it would not be detected. However, the main purpose of using THz is to see through packaging material and to see through clothing to find contraband strapped to somebody boarding a plane.

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