400 kHz repetition rate THz-TDS with 24 mW of average power driven by a compact industrial Yb-laser

TL;DR

This paper presents a high-power, high-repetition-rate THz-TDS system driven by a compact industrial Yb-laser, achieving up to 24 mW of THz power at 400 kHz with stable bandwidth and field strength, suitable for advanced spectroscopy.

Contribution

It introduces a novel THz-TDS setup using a commercial industrial laser with tunable repetition rate up to 400 kHz, demonstrating high power and stable bandwidth without thermal effects.

Findings

Achieved 24 mW of THz power at 400 kHz

Stable bandwidth across different repetition rates

High electric field strength suitable for spectroscopy

Abstract

We demonstrate a high average power terahertz time-domain (THZ-TDS) spectrometer based on optical rectification in the tilted-pulse front geometry in lithium niobate at room temperature, driven by a commercial, industrial femtosecond-laser operating with flexible repetition rate between 40 kHz - 400 kHz. The driving laser provides a pulse energy of 41 uJ for all repetition rates, at a pulse duration of 310 fs, allowing us to explore repetition rate dependent effects in our TDS. At the maximum repetition rate of 400 kHz, up to 16.5 W of average power are available to drive our THz source, resulting in a maximum of 24 mW of THz average power with a conversion efficiency of ~ 0.15 % and electric field strength of several tens of kV/cm. At the other available lower repetition rates, we show that the pulse strength and bandwidth of our TDS is unchanged, showing that the THz generation is not affected by thermal effects in this average power region of several tens of watts. The resulting combination of high electric field strength with flexible and high repetition rate is very attractive for spectroscopy, in particular since the system is driven by an industrial, compact laser without the need for external compressors or other specialized pulse manipulation.