Mankind has harnessed and used just about all of the electromagnetic spectrum. We have radar, microwave ovens, radios, cell phones, wireless communications, X-Rays, lasers, and so on. Yet, there is one area of the electromagnetic spectrum that has yet to be harnessed and exploited. This area is called the Terahertz Gap. It is an area that lies between microwave and infrared frequencies.
The terahertz band is defined as the portion of the electromagnetic spectrum between 0.3 THz and 10 THz, where one terahertz corresponds to one trillion (1012) oscillations per second. At the low end of the band at 0.3 THz the wavelength in free space is one millimeter; therefore, since the wavelength declines as the reciprocal of frequency, the terahertz band is frequently referred to as the sub millimeter wavelength band.
Well established technologies that work well at lower frequencies become inapplicable in the terahertz band because of the small wavelength, while classical infrared techniques become impractical because, from an optical perspective, the wavelength becomes too large. Because of the difficulty of operating in the terahertz band and because there had previously been no convenient sources of terahertz light, this part of the spectrum is frequently referred to as the “forbidden region” or the “Terahertz Gap”.
Actually, there are abundant sources of terahertz light. All warm bodies emit light in the infrared and the low frequency end of that spectrum is in the terahertz region. However, this thermal energy is randomly distributed and, therefore, has limited commercial uses (which require terahertz light that is coherently oriented). Just below the terahertz band are the microwave and millimeter wave bands and just above is the infrared band. Both of these segments of the electromagnetic spectrum have been exploited with great commercial success.
The terahertz band offers a breathtaking array of possible applications that go far beyond simply extending the familiar services that are well established in the neighboring regions of the electromagnetic spectrum. These applications have been demonstrated in the laboratory, but they have not been exploited commercially because of the lack (until now) of suitable sources of terahertz light and amplification.
Harmless Non-Ionizing Radiation (Low Human Safety Risk)
Compared to X-Ray, terahertz radiation is not harmful to humans. Ionizing radiation is characterized as having sufficient energy to remove an electron from an atom or molecule. Since THz light is non-ionizing, terahertz applications can be used safely and effectively.
- All warm bodies naturally emit THz radiation
- High frequency implies broad bandwidth and very high wireless data transmission rates
- Unprecedented, high resolution imaging
- Able to penetrate clothing and non-metallic materials up to 100 meters distant (normal air, fog and sandstorm conditions)
- THz radiation enables imaging through clothing, bandages, and packaging materials
- Unambiguous identification of molecular species (fingerprint)
- Complex molecules such as chem/bio agents and pathogens can be unambiguously identified in real time by their resonant signatures in THz band at stand-off distances
- Unique chemical signatures of molecular species for unambiguous identification (fingerprint capability)
- Distinctively different propagation of THz in different types of human tissue enables cancer detection
- Selective heating below surface of the skin will enabling wrinkle smoothing