Robust phase correction techniques for terahertz time-domain reflection spectroscopy

TL;DR

This paper presents robust phase correction methods for terahertz reflection spectroscopy using Kramers-Kronig relations, enabling accurate optical property estimation even with misaligned measurements.

Contribution

The authors develop two phase correction techniques that improve the accuracy of terahertz reflection measurements, applicable across various angles and polarizations.

Findings

Accurately retrieved the complex refractive index of InSb.

Demonstrated robustness against measurement misalignment.

Applicable to arbitrary incidence angles and polarization states.

Abstract

We introduce a systematic approach that enables two robust methods for performing terahertz time-domain spectroscopy in reflection geometry. Using the Kramers-Kronig relations in connection to accurate experimental measurements of the amplitude of the terahertz electric field, we show how the correct phase of the same field can be retrieved, even in the case of partly misaligned measurements. Our technique allows to accurately estimate the optical properties of in principle any material that reflects terahertz radiation. We demonstrate the accuracy of our approach by extracting the complex refractive index of InSb, a material with a strong plasma resonance in the low-terahertz range. Our technique applies to arbitrary incidence angles and polarization states.