Three Pole Auston Switch Terahertz Ellipsometer

A new spectroscopic instrument – a time-domain terahertz ellipsometer (TDTE) – and the associated techniques for characterization of advanced materials in the terahertz (THz) spectral range will be developed. A novel three pole Auston-type switch will serve as the detector which is capable of simultaneously measuring two electric field polarizations. Standard THz time domain spectroscopy requires transmission of the beam through the test sample and will not work for opaque materials. Ellipsometry measurements with the TDTE will overcome this limitation by directly detecting the polarization change of the incident beam after reflection due to the material properties of the target surface. During Phase I, the design, fabrication, and testing of the three pole Auston switch will be implemented. The TDTE system will be designed around the three pole switch. Benchmark measurements will be performed on opaque target materials that had been previously impossible to characterize with standard transmission THz spectroscopy. In Phase II, a compact fiber coupled TDTE will be designed and constructed, suitable for laboratory and commercial environments. Advanced analysis and automation controls will enable the TDTE to perform previously impossible measurements rapidly and with high precision.