University of Wisconsin-Madison Physical Sciences Lab

Material Characterization System

Yang/Booske MCS

The Physical Sciences Laboratory has partnered in the development of a terahertz-frequency regime (100-3,000 gigahertz) material characterization system by Benjamin Yang, Sarah Katz and John Booske of the Electrical and Computer Engineering Department at the University of Wisconsin-Madison. The system can be used to measure electromagnetic properties–such as dielectric constant, loss tangent and conductivity–of materials by detecting changes in the resonance characteristics of a quasi-optical resonator. Since there are few off-the-shelf parts for use in the terahertz regime, the Physical Sciences Laboratory has custom-fabricated many components of the experiment, shown above. Examples include the large copper mirror, the frame holding the thin film beam splitter, the sample holder, and the stainless steel posts supporting the electromagnetic source, allowing it to be reasonably aligned with little effort. Already, the system has been used to measure material parameters of thin dielectrics, as well as changes in conductivity between gold and steel. Once operating at optimal parameters, this system will be used to tackle the unexplored question of how surface roughness affects conductivity at terahertz frequencies. The project is funded by the Air Force Office of Scientific Research.