A custom-tailored multi-TW optical electric field for gigawatt soft-x-ray isolated attosecond pulses

TL;DR

This paper demonstrates a stable, high-power multi-TW optical waveform synthesizer that enables the generation of gigawatt-scale soft-x-ray isolated attosecond pulses through high-order harmonic generation, advancing attosecond science capabilities.

Contribution

It introduces a three-channel TW-class optical synthesizer with stabilization methods, achieving stable, high-energy waveforms for generating intense, isolated attosecond pulses in the soft-x-ray region.

Findings

Generation of 170 as IAP with 50-70 eV supercontinuum.

Production of 106 as IAP with 100-130 eV supercontinuum.

Demonstration of stable, high-peak-power optical waveform synthesis.

Abstract

The bottleneck for an attosecond science experiment is concluded to be the lack of a high-peak-power isolated attosecond pulse source. Therefore, currently, generating an intense attosecond pulse would be one of the highest priority goals. In this paper, we review a TW-class parallel three-channel waveform synthesizer for generating a gigawatt-scale soft-x-ray isolated attosecond pulse (IAP) using high-order harmonics generation (HHG). Simultaneously, using several stabilization methods, namely, the low-repetition-rate laser carrier-envelope phase stabilization, Mach-Zehnder interferometer, balanced optical cross-correlator, and beam-pointing stabilizer, we demonstrate a stable 50-mJ three-channel optical-waveform synthesizer with a peak power at the multi-TW level. This optical-waveform synthesizer is capable of creating a stable intense optical field for generating an intense continuum harmonic beam thanks to the successful stabilization of all the parameters. Furthermore, the precision control of shot-to-shot reproducible synthesized waveforms is achieved. Through the HHG process employing a loose-focusing geometry, an intense shot-to-shot stable supercontinuum (50-70 eV) is generated in an argon gas cell. This continuum spectrum supports an IAP with a transform-limited duration of 170 as and a submicrojoule pulse energy, which allows the generation of a GW-scale IAP. Another supercontinuum in the soft-x-ray region with higher photon energy of approximately 100-130 eV is also generated in neon gas from the synthesizer. The transform-limited pulse duration is 106 as. According to this work, the enhancement of HHG output through optimized waveform synthesis is experimentally proved. The high-energy multicycle pulse with 10-Hz repetition rate is proved to have the same controllability for optimized waveform synthesis for HHG as few- or subcycle pulses from a 1-kHz laser.