Self-Synchronized Terahertz and X-Ray Free-Electron Lasers from a Single Pre-Bunched Electron Beam

Yin Kang; Kaiqing Zhang; Zhen Wang; Cheng Yu; Zhangfeng Gao; Wencai Cheng; Hang Luo; Yue Wang; Hanghua Xu; Xiaoqing Liu; Jinguo Wang; Huan Zhao; Yanyan Zhu; Yongmei Wen; Fei Gao; Yangyang Lei; Chengcheng Xiao; Liping Sun; Yongfang Liu; Jiaqiang Xu; Weiyi Yin; Xingtao Wang; Taihe Lan; Zheng Qi; Tao Liu; Zhi Guo; Bin Li; Chao Feng; Bo Liu; Zhentang Zhao

arXiv · 2608.15106

Self-Synchronized Terahertz and X-Ray Free-Electron Lasers from a Single Pre-Bunched Electron Beam

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Abstract

Ultrafast pump-probe spectroscopy combining intense terahertz (THz) and X-ray pulses is a critical tool for investigating complex structural and electronic dynamics in materials. However, current setups combining THz sources and X-ray free-electron lasers (FELs) often suffer from high system complexity, inherent timing jitter, or limited THz pulse properties. Here, we experimentally demonstrate the generation of intrinsically synchronized, strong-field, narrow-band THz and X-ray FELs from a single pre-bunched electron beam. Sequentially passing the beam through X-ray and THz amplifiers reveals a highly synergistic process: the initial periodic THz density modulation notably boosts the X-ray FEL pulse energy, while robustly surviving the intense X-ray emission to drive high-power, narrow-band THz radiation. Originating from the same electron bunch, the two pulses inherently maintain a precise, constant time delay. This jitter-free scheme establishes a highly reliable platform tailored for both X-ray-pump/THz-probe and THz-pump/X-ray-probe experiments.

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Yin Kang, Kaiqing Zhang, Zhen Wang, Cheng Yu, Zhangfeng Gao, Wencai Cheng, Hang Luo, Yue Wang, Hanghua Xu, Xiaoqing Liu, Jinguo Wang, Huan Zhao, Yanyan Zhu, Yongmei Wen, Fei Gao, Yangyang Lei, Chengcheng Xiao, Liping Sun, Yongfang Liu, Jiaqiang Xu, Weiyi Yin, Xingtao Wang, Taihe Lan, Zheng Qi, Tao Liu, Zhi Guo, Bin Li, Chao Feng, Bo Liu, Zhentang Zhao. 2026-08-15. Self-Synchronized Terahertz and X-Ray Free-Electron Lasers from a Single Pre-Bunched Electron Beam. https://arxiv.org/abs/2608.15106

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