Demonstration of direct-amplification enabled harmonic generation in an ultraviolet free-electron laser
We report the experimental demonstration of direct-amplification enabled harmonic generation in an ultraviolet free-electron laser (FEL) driven by a low-intensity seed laser. By employing a versatile undulator configuration that enables seed amplification and harmonic generation within a unified setup, we achieved over 100-fold energy gain of the seed and observed exponential growth at the second harmonic. The results demonstrate that a sufficiently long modulator cannot only amplify a weak seed but also induce strong energy modulation of the electron beam, enabling efficient harmonic bunching. This method markedly relaxes the power requirements on external seed lasers and presents a viable route toward high-repetition-rate, fully coherent FELs.
Authors
- Zequn Wang (ORCID: https://orcid.org/0009-0005-0037-3098)
- Jitao Sun (ORCID: https://orcid.org/0009-0007-0980-774X)
- Xueming Yang (ORCID: https://orcid.org/0000-0001-6684-9187)
- Hao Sun (ORCID: https://orcid.org/0000-0003-2578-2371)
- Guorong Wu (ORCID: https://orcid.org/0000-0002-0212-183X)
- Yingyu Liang (ORCID: https://orcid.org/0009-0005-8374-0753)
- Lingjun Tu (ORCID: https://orcid.org/0000-0002-9345-0590)
- Qinming Li (ORCID: https://orcid.org/0000-0001-8420-8746)
- Weiqing Zhang (ORCID: https://orcid.org/0000-0001-6518-4152)
- Xiaofan Wang (ORCID: https://orcid.org/0000-0002-2670-5119)
- Huaiqian Yi (ORCID: https://orcid.org/0009-0001-9168-5505)
- Likai Wang (ORCID: https://orcid.org/0000-0002-9898-3839)
- Li Zeng (ORCID: https://orcid.org/0009-0005-0024-849X)
- Yong Yu (ORCID: https://orcid.org/0009-0004-3061-9207)
- Yuhuan Tian
- Jiayue Yang (ORCID: https://orcid.org/0009-0000-0954-1231)
- Zhigang He
Institutions
- Dalian Institute of Chemical Physics (CN)
- Southern University of Science and Technology (CN)
- Shenzhen Institutes of Advanced Technology (CN)
Publication Details
- Journal
- Applied Physics Letters
- Published
- 2025-11-03
- DOI
- https://doi.org/10.1063/5.0287044
- Primary Topic
- Particle Accelerators and Free-Electron Lasers
- Type
- article
- Field-Weighted Citation Impact
- 0.00