Femtosecond THz time domain spectroscopy at 36 kHz scan rate using an acousto-optic delay

TL;DR

This paper introduces a high-speed, femtosecond THz time-domain spectrometer with an acousto-optic delay, enabling rapid real-time THz measurements and dynamic process monitoring with high precision and stability.

Contribution

It presents a novel rapid-scan THz spectrometer using femtosecond Er:fiber technology and acousto-optic delay, achieving 36 kHz scan rate and real-time dynamic process monitoring.

Findings

Achieved 36 kHz scan rate for THz waveform acquisition.

Demonstrated real-time 2D thickness mapping with 10 nm/√Hz precision.

Ensured alignment-free operation suitable for harsh environments.

Abstract

We present a rapid-scan, time-domain terahertz spectrometer employing femtosecond Er:fiber technology and an acousto-optic delay with attosecond precision, enabling scanning of terahertz transients over a 12.4 ps time window at a waveform refresh rate of 36 kHz, and a signal-to-noise ratio of $1.7 \times 10^5/\sqrt{\rm Hz}$. Our approach enables real-time monitoring of dynamic THz processes at unprecedented speeds, which we demonstrate through rapid 2D thickness mapping of a spinning teflon disc at a precision of $10\,\rm nm/\sqrt{\rm Hz}$. The compact, all-optical design ensures alignment-free operation even in harsh environments.