Developments in THz range ellipsometry

TL;DR

This review highlights recent advances in terahertz ellipsometry, a technique for characterizing material optical properties at THz frequencies, overcoming technical challenges and exploring various configurations and applications.

Contribution

It provides a comprehensive overview of recent developments and methodologies in THz ellipsometry, including experimental setups and practical applications.

Findings

Successful implementation of THz ellipsometry techniques

Various configurations using continuous wave and pulsed sources

Identification of challenges and solutions in THz range measurements

Abstract

Ellipsometry is a technique whereby the measurement of the two orthogonal polarization components of light reflected at glancing incidence allows a characterization of the optical properties of a material at a particular frequency. Importantly, it obviates the need for measurement against a standard reference sample, and so can provide reliable spectroscopic information even when surface morphology is unknown, of marginal quality and/or a reference is unavailable. Although a standard technique in the visible range, it has not been widely applied in the Terahertz (THz) spectral range despite its potential utility. This is largely because of the technical difficulties that these frequencies present. This review details recent progress in the implementation of THz range ellipsometry. We discuss a variety of configurations including various kinds of laboratory and facility based sources using both continuous wave and pulsed spectroscopic methods. We discuss the general problems encountered when trying to import the methodologies of visible range ellipsometry to the THz range and give examples of where the technique has been successful thus far.