Polarization modulation time-domain terahertz polarimetry

TL;DR

This paper introduces a high-precision, time-domain terahertz polarimetry method using polarization modulation and lock-in detection to accurately measure polarization rotations across a broad frequency range.

Contribution

It presents a novel polarization modulation technique with high accuracy and precision for characterizing elliptical polarizations in the terahertz frequency range.

Findings

Achieved 0.05° accuracy in polarization rotation measurements.

Demonstrated full characterization of elliptical polarizations from 0.1 to 2.5 THz.

Developed a detailed mathematical model of the measurement technique.

Abstract

We present high precision measurements of polarization rotations in the frequency range from 0.1 to 2.5 THz using a polarization modulation technique. A motorized stage rotates a polarizer at ~80 Hz, and the resulting modulation of the polarization is measured by a lock-in technique. We achieve an accuracy of 0.05{\deg} (900 {\mu}rad) and a precision of 0.02{\deg} (350 {\mu}rad) for small rotation angles. A detailed mathematical description of the technique is presented, showing its ability to fully characterize elliptical polarizations from 0.1 to 2.5 THz.