The response of materials to electromagnetic waves in the millimeter (mm) and sub-millimeter (smm) wavelength range (from approximately 50 to 500 GHz) has received relatively little study. An understanding of the nature and origin of absorption in materials at these wavelengths has basic significance for solid state physics as well as importance for RF technology. Current emphasis is on the experimental determination of the predominant mechanisms of absorption for millimeter and submillimeter electromagnetic waves in high gap semiconductors, especially CVD diamond and SiC. In order to identify the impurities or defects that give rise to the excess loss, temperature-dependent conductivity and DLTS measurements are being undertaken on candidate materials. Dielectric loss measurements over a wide range of temperatures and frequencies are performed to verify the results obtained from electrical methods and help to determine the primary loss mechanisms for the materials under investigations. Shown below is a system comprised of a BWO source, a high Q resonator, and a spectrum analyzer used to measure losses as 10-6 in the submillimeter wavelength regime.

Some recent publications:

1. “Characterization of Low loss Materials,” J.M.Dutta and C.R. Jones, Materials, Integration and Packaging Issues for High-Frequency Devices II, Eds. Yong S. Cho, Don Shiffler, Clive A. Randall, Harrie A.C.Tilmans, and Takaaki Tsurumi, MRS Volume 833, 2005.
2. “The Mechanisms of Absorption in High-Gap Semiconductors at Millimeter and submillimeter Wavelengths,” J. M. Dutta, G. Yu, and C. R. Jones, Proc. 32nd Int. Conf. on IRMMW and 15th Int. Conf. on THz Electronics, Cardiff, UK 2007
3. “Synchronization of a Millimeter-wave BWO With a Spectrum Analyzer Via A Simple Phaselock System,” Proc. 32nd Int. Conf. on IRMMW and 15th Int. Conf. on THz Electronics, Cardiff, UK 2007

Copyright © 2004  Department of Physics ! All Rights Reserved.