Terahertz Gas Spectroscopy Applied to Medicine and Metrology

Abstract

The following characteristics of the terahertz (THz) frequency range are very favorable for various gas spectroscopy applications, which is based on excitations of rotational transitions by the THz waves. First, this technique is highly sensitive enabling the detection of low concentrations of volatile organic compounds (VOCs). Second, numerous gases can be unambiguously identified, because they reveal fingerprint spectra in this frequency region. Third, the identification of each gas is very specific. From the technological perspective, the ongoing developments of high-frequency silicon-based circuits, such as complementary metal-oxide semiconductor (CMOS) or Silicon-Germanium Bipolar CMOS (SiGe BiCMOS), will push applications as they can be easily integrated in the baseband electronics and can be produced at moderate costs in high quantities [1], [2]. Therefore, THz spectroscopy will likely find its way to everyday applications in the near future.

In this article, we will describe recent results regarding miniaturized THz systems based on SiGe BiCMOS circuits and its impact on potential application in the fields of medicine and metrology, namely for breath analysis and frequency standards. We will present the technical background and key requirements of the systems as well as their performances for the aforementioned applications.