Correction of systematic low-frequency time delay errors in THz systems by absorption line shape optimization.

Time-domain terahertz systems can face challenges due to systematic delay errors introduced by the employed delay mechanism, potentially leading to poor data quality. This article introduces a procedure to address these challenges by correcting low-frequency systematic errors that distort the acquired spectra and incorrectly diminish narrow absorption features. Our procedure solves an optimization problem aiming to find the corrected time-signal pairs that maximize the depth of narrow absorption features, and we highlight how the flexibility of the procedure, in principle, allows for correcting error profiles of arbitrary shape.

Fourier-transform THz spectroscopy based on electric-field interferometry using THz-PMT.

We demonstrate a high dynamic range (DR) Fourier-transform-based terahertz (THz) spectrometer by combining a THz photomultiplier tube (PMT) with a metasurface and a conventional Michelson interferometer. Because the THz-PMT response depends on the incident electric-field strength following the Fowler-Nordheim equation, we can directly obtain an electric field interferogram without any synchronized optical probe pulse in contrast to conventional THz-time-domain-spectroscopy (THz-TDS). The DR of the corresponding power spectrum using the proposed method was 4.

Terahertz Cross-Correlation Spectroscopy and Imaging of Large-Area Graphene.

We demonstrate the use of a novel, integrated THz system to obtain time-domain signals for spectroscopy in the 0.1-1.4 THz range.