Developments in Terahertz Ellipsometry: Portable Spectroscopic Quasi-Optical Ellipsometer-Reflectometer and Its Applications

The paper presents a new instrument—a portable spectroscopic quasi-optical (QO) THz ellipsometer-reflectometer (SQOTER). It combines two independent experimental techniques: THz ellipsometry and reflectometry. SQOTER is based on the hollow dielectric beamguide and beamguide components as a QO transmission line. This ultra-broadband line provides operation of the setup within 0.1…1 THz frequency range. The setup provides measurements of the ellipsometric parameters (at variable incidence angle) and the reflection coefficient (at normal incidence) in the wide spectral range. A detailed analysis of the spectral characteristics of QO transmission line and components was carried out. The principles and details of SQOTER measurements were described and its accuracy was estimated. A special system based on a silicon wafer was created for SQOTER testing. Reflection coefficients of this system measured independently by ellipsometry and reflectometry were compared and showed good agreement. The portable SQOTER capabilities connected with research and industrial applications have been demonstrated.