Request a Quote

Accurate THz ellipsometry using calibration in time domain

Zahra Mazaheri, Can Koral & Antonello Andreone
Scientific Reports
12,
7342
(2022)
Open access
© The Author(s) · CC BY 4.0
First page of Mazaheri et al. 2022, Scientific Reports
Mazaheri et al. (2022)
Scientific Reports 12, 7342
Read the published paper

Research overview

This paper presents a customised terahertz time-domain spectroscopic ellipsometer (THz-TDSE) for accurate material characterisation over a wide range of incidence angles. The fibre-coupled system incorporates three free-standing wire-grid polarizers and an algorithm-assisted time-domain calibration method to compensate for imperfect antenna and polarizer response, imprecise angular positioning and mismatches in the THz beam optics. Measurements on solid and liquid samples demonstrated good agreement with conventional THz time-domain spectroscopy, showing the potential of calibrated THz ellipsometry for characterising highly absorptive materials that are difficult to investigate in transmission.

Key findings

  • Variable-angle THz time-domain ellipsometry over approximately 0.1–0.6 THz
  • Three free-standing wire-grid polarizers used as polarizer, analyzer and compensator
  • Algorithm-assisted calibration compensates polarization and optical-system non-idealities
  • Measurements validated on solid and liquid materials against conventional THz spectroscopy
Purewavepolarizer 10 micron wire grid polarizer image

10 µm Tungsten Wire-Grid Polarizer

Free-standing tungsten wire-grid polarizer used for broadband THz polarization control. Three polarizers were employed in the ellipsometer as polarizer, analyzer and compensator.
View product configurations
“For the control and detection of the polarization states we employ three substrate free Wire Grid Polarizers (WGP) from PureWavePolarizers Ltd, with broadband transmission and high extinction ratio ranging between 20 and 50 dB.”
Mazaheri et al.,
2022

Publication details

Journal

Scientific Reports

Volume

12

Issue

–

Article

7342

Published

2022

Research area

Instrumentation and Metrology

Application

THz ellipsometry and material characterisation

Licence

© The Author(s) · CC BY 4.0

Institution

University of Naples Federico II / INFN Naples

DOI

https://doi.org/10.1038/s41598-022-10804-w

Related research

First page of Djevahirdjian et al. 2023, Nature Communications

Frequency stable and low phase noise THz synthesis for precision spectroscopy

A photomixing THz source tunable from 0.1 to 1.4 THz, with Hz-level linewidth and mHz/s stability, resolves 10 kHz-wide hyperfine Lamb dips in water at 556.9 GHz. A polarizing grid separated the double-pass beam in the sub-Doppler setup.
View publication →
Placeholder image for a Spectroscopy and Molecular Physics publication

Tunneling motion and splitting in the CH₂OH radical: (Sub-)millimeter wave spectrum analysis

The tunnelling motion of the CH₂OH radical is analysed from new 140–900 GHz spectra and ab initio calculations, determining its ground-state tunnelling splitting. A Purewave wire-grid polarizer enabled a double pass through the 2 m absorption cell.
View publication →
View all research publications →