Boston Chapter of the IEEE Photonics Society

Wed
Nov 2, 2005
7:45 PM
 

MIT Lincoln Laboratory
 

Measurement Aspects of Terahertz Technologies

Dr. Eyal Gerecht, NIST, Boulder, CO

Abstract:  Imaging and spectroscopy at terahertz frequencies (defined roughly as 300 GHz – 3 THz) have great potential for both healthcare and homeland security applications. Terahertz frequencies correspond to the rotational energy level transitions of important molecules in biology and astrophysics. Terahertz radiation (T-rays) can penetrate clothing and, to some extent, can also penetrate biological materials, and because of their shorter wavelengths they offer higher spatial resolution than microwaves or millimeter waves.  However, development of terahertz technologies is impeded or even prevented by the lack of standards and the inability to perform precise measurements to characterize noise, power, dielectric constants, and scattering parameters of systems and components operating at terahertz frequencies. Without noise characterization capability, for example, it is impossible to separate signal from background. This problem is particularly challenging in the terahertz range, which lies between the microwave/millimeter-wave range and the infrared range, both of which have well developed methods and technology for measuring noise and sensitivity. However, neither set of tools for noise measurements can be extended directly to terahertz frequencies.  In addition, the dominant source for noise in electronic systems at terahertz frequencies, other than thermal noise, which is dominant at microwave and millimeter-wave frequencies, is quantum noise due to vacuum fluctuations, which dominates at optical frequencies.  In the terahertz range, both quantum and thermal noise are important and must be dealt with. Similar arguments can be applied to power and material measurements at terahertz frequencies.  I will discuss in detail measurement techniques currently available at terahertz frequencies. In addition, I will describe the work in progress at NIST aimed to provide better tools for the development of terahertz technologies in the future.

Biography:  Dr. Eyal Gerecht received his Ph.D. degrees in Electrical and Computer Engineering from the University of Massachusetts at Amherst in 1998. In 1998, he joined the Department of Physics and Astronomy at the University of Massachusetts at Amherst as a Senior Postdoctoral Research Associate. Since 2000, he has been a physicist in the Electromagnetics Division at the National Institute of Standards and Technology, Boulder, CO. developing a number of terahertz technologies for imaging and spectroscopy for homeland security and biomedical applications.  Dr. Eyal Gerecht is one of the US leaders in the development of the near quantum-noise limited phonon-cooled HEB mixer receivers, funded primarily by NASA and NSF. Dr. Gerecht is a Co-PI of the successful development and installation (in 2002-2003) at the US South Pole Station of the 1.25 THz to 1.5 THz spectroscopical receiver system (TREND).