Detection of Terahertz Radiation from Submicron Plasma Waves Transistors

Abstract

Terahertz (THz) rays are located in the spectral region ∼ 0.1-10 THz (∼ 3 mm 30 μm, 3 cm−1 300 cm−1) between the microwave and the infrared portion of the electromagnetic spectrum. Detection and emission of terahertz radiation bears great potential in medical diagnostics, product quality control and security screening. The attractive features of THz radiation for applications are: (i) They are transmitted by cloths andmost packagingmaterials such as paper or plastics (ii) Many substances have fingerprint spectra in the THz range (iii) Due to its low photon energy (about one million times less than X-rays), THz radiation is non-ionizing and therefore not dangerous for human beings. These properties make THz systems a promising tool for different types of applications wherever detection and identification of hidden threats is the task and when human beings are to be scanned. When T-rays strike an object some of the rays pass through and others bounce back. A detector can measure the time it takes for rays to bounce back from different layers of an object. From that information, computers can produce a three dimensional image of the objects internal structure. The detectors can also identify the color shift of the reflecting rays. Every chemical and material has a unique color signature (fingerprint), so THz systems can determine not just what an object looks like, but what it’s made of. THz rays may have dozens of practical applications, from medical imaging to wireless communications (Tonouchi, 2007). New terahertz system for scanning mails is under trial in Japan (Hoshina et al., 2009). Kawase et al. has demonstrated non-destructive terahertz imaging of illicit drugs (Kawase et al., 2003). An excellent review highlighting the importance of terahertz range in different types of applications from astronomy to spectroscopy can be found in Siegel (Siegel, 2002) and references in.