Gas-plasma based generation of broadband THz radiation with 640 mW average power

TL;DR

This paper reports a high-power broadband THz radiation source with 640 mW average power, achieved through advanced gas plasma generation driven by a state-of-the-art fiber laser system, enabling new applications in spectroscopy and nonlinear studies.

Contribution

The authors demonstrate the highest THz average power to date using a two-color gas plasma process driven by a coherent combination of high-energy fiber amplifiers.

Findings

Achieved 640 mW average power in broadband THz radiation.

Implemented a gas-jet scheme for increased efficiency.

Characterized the full THz bandwidth using air-biased-coherent-detection.

Abstract

We present a high-power source of broadband terahertz radiation covering the whole THz spectral region (0.1-30 THz). The two-color gas plasma generation process is driven by a state-of-the-art Ytterbium fiber chirped pulse amplification system based on coherent combination of 16 rod-type amplifiers. Prior to the THz generation, the pulses are spectrally broadened in a multi-pass-cell and compressed to 37 fs with a pulse-energy of 1.3 mJ at a repetition rate of 500 kHz. A gas-jet scheme has been employed for the THz generation, increasing the efficiency of the process to 0.1%. The air-biased-coherent-detection scheme is implemented to characterize the full bandwidth of the generated radiation. A THz average power of 640 mW is generated, which is the highest THz average power achieved to date. This makes this source suitable for a variety of applications, e.g. spectroscopy of strongly absorbing samples or driving nonlinear effects for the studies of material properties.