Isolated Attosecond Free-Electron Laser Based on a Subcycle Driver from Hollow Capillary Fibers

An attosecond light source provides an advanced tool for investigating electron motion using time-resolved-spectroscopy techniques. Isolated attosecond pulses, especially, will significantly advance the study of electron dynamics. However, achieving high-intensity isolated attosecond pulses is still...

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Bibliographic Details
Main Authors: Yaozong Xiao, Tiandao Chen, Bo Liu, Zhiyuan Huang, Meng Pang, Yuxin Leng, Chao Feng
Format: Article
Language:English
Published: American Association for the Advancement of Science (AAAS) 2025-01-01
Series:Ultrafast Science
Online Access:https://spj.science.org/doi/10.34133/ultrafastscience.0099
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Summary:An attosecond light source provides an advanced tool for investigating electron motion using time-resolved-spectroscopy techniques. Isolated attosecond pulses, especially, will significantly advance the study of electron dynamics. However, achieving high-intensity isolated attosecond pulses is still challenging at the present stage. In this paper, we propose a novel scheme for generating high-intensity, isolated attosecond soft x-ray free-electron lasers (FELs) using a mid-infrared (MIR) subcycle modulation laser from gas-filled hollow capillary fibers. The multi-cycle MIR pulses are first compressed to subcycles using a krypton-filled hollow capillary fiber with a decreasing pressure gradient due to the soliton self-compression effect. By utilizing such subcycle MIR laser pulses to modulate an electron beam, we can obtain a quasi-isolated current peak, which can then produce an isolated FEL pulse with a high signal-to-noise ratio, naturally synchronizing with the subcycle MIR laser pulse. Numerical simulations have been carried out, including subcycle pulse generation, electron beam modulation, and FEL radiation processes. The simulation results indicate that an isolated attosecond pulse with a wavelength of 1 nm, a peak power of ~28 GW, a pulse duration of ~580 as, and a signal-to-noise ratio of ~96.2% can be generated by our proposed method. The numerical results demonstrated here pave a new way for generating a high-intensity isolated attosecond soft x-ray pulse, which may have many applications in nonlinear spectroscopy and atomic-site electronic processes.
ISSN:2765-8791