Precise and accurate control of the ellipticity of THz radiation using a photoconductive pixel array

TL;DR

This paper demonstrates precise control over the ellipticity of broadband THz pulses using a four-pixel photoconductive emitter with an integrated achromatic waveplate, achieving high polarization purity and accuracy.

Contribution

It introduces a novel method for full polarization control of broadband THz radiation with high accuracy and a new figure of merit for measurement precision.

Findings

Achieved polarization purity exceeding 97% for linear and circular states.

Demonstrated full control of ellipticity from linear to circular polarization.

Introduced a new measurement precision metric with a standard error of 0.047° after one second.

Abstract

Full control of the ellipticity of broadband pulses of THz radiation, from linear to left- or right-handed circular polarization, was demonstrated via a 4-pixel photoconductive emitter with an integrated achromatic waveplate. Excellent polarization purity and accuracy was achieved, with Stokes parameters exceeding 97% for linear and circular polarization, via a robust scheme that corrected electrically for polarization changes caused by imperfect optical elements. Further, to assess the speed and precision of measurements of the THz polarization we introduced a new figure of merit, the standard error after one second of measurement, found to be 0.047$^{\circ}$ for the polarization angle.