- Physical Review Journals
All JournalsPhysics Magazine

Physical Review Accelerators and Beams

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access

Wavelength switching and scanning of the high-gain harmonic generation free-electron laser at the Dalian Coherent Light Source

Xinmeng Li1,2, Yong Yu3,*, Qinming Li3, Siyue Liu1,4, Chong Wang1,3, Jiami Zhou1, Feiyang Yin1, Xu Shi1, Jitao Sun3 et al.

Jiahang Shao3, Xiaofan Wang3, Zhigang He1, Wenrui Dong1, Ling Jiang1, Jiayue Yang1,†, Guorong Wu1, Weiqing Zhang1,‡, and Xueming Yang1

  • *Contact author: yuyong@mail.iasf.ac.cn
  • †Contact author: yjy@dicp.ac.cn
  • ‡Contact author: weiqingzhang@dicp.ac.cn
PDF

Phys. Rev. Accel. Beams 28, 100701 – Published 9 October, 2025

DOI: https://doi.org/10.1103/2wmp-cb2b

Abstract

The continuous wavelength tunability of free-electron lasers (FELs) offers significant potential for research across various scientific fields. The Dalian Coherent Light Source (DCLS), when operating in the high-gain harmonic generation (HGHG) mode, has demonstrated wavelength tuning capability within the vacuum ultraviolet (VUV) range of 50–150 nm. To address diverse experimental demands, it is imperative to have the capability of fast wavelength switching and scanning. This study presents three wavelength tuning strategies experimentally implemented at DCLS, each characterized by specific tuning ranges and resolutions: (i) full-range continuous wavelength switching over 50–150 nm, typically requiring more than 2 h; (ii) wide-range coarse wavelength scanning with approximately 20% variation within several minutes; and (iii) narrow-range fine wavelength scanning with a range of about 0.44% and a scanning resolution of 0.01% in less than 1 min. Each strategy has its own advantages and limitations, and their combination significantly enhances the flexibility of wavelength manipulation at DCLS, accommodating diverse user requirements.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (51)

  1. W. A. Ackermann et al., Operation of a free-electron laser from the extreme ultraviolet to the water window, Nat. Photonics 1, 336 (2007).
  2. A. Brachmann, Commissioning of LCLS-II, in Proceedings of the 32nd Linear Accelerator Conference, LINAC-2024, Chicago, IL (JACoW, Geneva, Switzerland, 2024), p. 589.
  3. E. Allaria et al., Highly coherent and stable pulses from the FERMI seeded free-electron laser in the extreme ultraviolet, Nat. Photonics 6, 699 (2012).
  4. W. Decking et al., A MHz-repetition-rate hard x-ray free-electron laser driven by a superconducting linear accelerator, Nat. Photonics 14, 391 (2020).
  5. B. Liu et al., The SXFEL upgrade: From test facility to user facility, Appl. Sci. 12, 176 (2022).
  6. Z. T. Zhao, H. Ding, and B. Liu, Shanghai Hard X-Ray FEL facility progress status, in Proceedings of the 15th International Particle Accelerator Conference, IPAC-2024, Nashville, TN (JACoW, Geneva, Switzerland, 2024), p. 967.
  7. X. Wang et al., Physical design for Shenzhen Superconducting Soft X-Ray Free-Electron Laser (S3FEL), in Proceedings of the 14th International Particle Accelerator Conference, Venice, Italy (JACoW, Geneva, Switzerland, 2023), p. 1852.
  8. X. Li et al., An injector testbed based on a direct current gun and an interchangeable very high frequency gun for superconducting continuous-wave free-electron lasers, J. Synchrotron Radiat. 32, 838 (2025).
  9. Y. Yu et al., Dalian extreme ultraviolet coherent light source, Chin. J. Lasers (Chin. Ed.) (1983–) 46, 0100005 (2019).
  10. J. Sun, X. Li, J. Yang, L. Zeng, J. Shao, Y. Yu, W. Zhang, and X. Yang, An experimental application of machine learning algorithms to optimize the FEL lasing via beam trajectory tuning at Dalian Coherent Light Source, Nucl. Instrum. Methods Phys. Res., Sect. A 1063, 169320 (2024).
  11. A. M. Kondratenko and E. L. Saldin, Generating of coherent radiation by a relativistic electron beam in an ondulator, Part. Accel. 10, 207 (1980), https://scispace.com/papers/generating-of-coherent-radiation-by-a-relativistic-electron-2dvmlgxc2w.
  12. R. Bonifacio, P. Pierini, C. Pellegrini, J. Rosenzweig, and G. Travish, Slippage, noise and superradiant effects in the UCLA FEL experiment, Nucl. Instrum. Methods Phys. Res., Sect. A 341, 285 (1994).
  13. L. H. Yu, Generation of intense UV radiation by subharmonically seeded single-pass free-electron lasers, Phys. Rev. A 44, 5178 (1991).
  14. L. H. Yu et al., First ultraviolet high-gain harmonic-generation free-electron laser, Phys. Rev. Lett. 91, 074801 (2003).
  15. J. Quan et al., A free electron laser-based 1+1′ resonance-enhanced multiphoton ionization scheme for rotationally resolved detection of OH radicals with correct relative intensities, J. Mol. Spectrosc. 380, 111509 (2021).
  16. F. Bencivenga et al., Reflectivity enhancement in titanium by ultrafast XUV irradiation, Sci. Rep. 4, 4952 (2014).
  17. F. Bencivenga, F. Capotondi, E. Principi, M. Kiskinova, and C. Masciovecchio, Coherent and transient states studied with extreme ultraviolet and x-ray free electron lasers: Present and future prospects, Adv. Phys. 63, 327 (2014).
  18. M. Malvestuto, R. Ciprian, A. Caretta, B. Casarin, and F. Parmigiani, Ultrafast magnetodynamics with free-electron lasers, J. Phys. Condens. Matter 30, 053002 (2018).
  19. Y. Zhao et al., Rotational and nuclear-spin level dependent photodissociation dynamics of H2S, Nat. Commun. 12, 4459 (2021).
  20. Y. Wu et al., Photodissociation dynamics of SO2 via the G˜1B1 state: The O(1D2) and O(1S0) product channels, J. Chem. Phys. 160 (2024).
  21. B. Liu et al., Demonstration of a widely-tunable and fully-coherent high-gain harmonic-generation free-electron laser, Phys. Rev. ST Accel. Beams 16, 020704 (2013).
  22. E. Allaria et al., Tunability experiments at the FERMI@Elettra free-electron laser, New J. Phys. 14, 113009 (2012).
  23. F. Sottocorona et al., Wavelength control in high-gain harmonic generation seeded free-electron lasers, Phys. Rev. Accel. Beams 26, 090702 (2023).
  24. B. Faatz et al., Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator, New J. Phys. 18, 062002 (2016).
  25. B. Faatz et al., The FLASH facility: Advanced options for FLASH2 and future perspectives, Appl. Sci. 7, 1114 (2017).
  26. T. Shaftan et al., Experimental demonstration of wavelength tuning in high-gain harmonic generation free electron laser, in Proceedings of the 26th International Free Electron Laser Conference, Trieste, Italy (JACoW, Geneva, Switzerland, 2004), p. 282.
  27. T. Shaftan and L. H. Yu, High-gain harmonic generation free-electron laser with variable wavelength, Phys. Rev. E 71, 046501 (2005).
  28. L. Zheng et al., Development of S-band photocathode RF guns at Tsinghua University, Nucl. Instrum. Methods Phys. Res., Sect. A 834, 98 (2016).
  29. A. Einstein, Concerning an heuristic point of view toward the emission and transformation of light, Am. J. Phys. 33, 367 (1965).
  30. Y. Yu et al., The X-band linear compression system in Dalian Coherent Light Source, in Proceedings of the 39th Free Electron Laser Conference, FEL2019, Hamburg, Germany (JACoW, Geneva, Switzerland, 2019), p. 625.
  31. G. Wang, C. Feng, H. Deng, T. Zhang, and D. Wang, Beam energy chirp effects in seeded free-electron lasers, Nucl. Instrum. Methods Phys. Res., Sect. A 753, 56 (2014).
  32. V. Balandin, W. Decking, and N. Golubeva, Optics for the beam switchyard at the European XFEL, in Proceedings of the 2nd International Particle Accelerator Conference, IPAC-2011, San Sebastián, Spain (EPS-AG, Spain, 2011), pp. 2016.
  33. K. Halbach, Permanent magnet undulators, J. Phys. (Paris), Colloq. 44, C1-211 (1983).
  34. C. Hwang and S. Yeh, Various polarization features of a variably polarized undulator with different phasing modes, Nucl. Instrum. Methods Phys. Res., Sect. A 420, 29 (1999).
  35. M. Weiss et al., The elliptically polarized undulator beamlines at BESSY II, Nucl. Instrum. Methods Phys. Res., Sect. A 467–468, 449 (2001).
  36. P. Schmüser, M. Dohlus, and J. Rossbach, Ultraviolet and Soft X-ray Free-Electron Lasers: Introduction to Physical Principles, Experimental Results, Technological Challenges (Springer, New York, 2008), Vol. 229.
  37. C. Li, S. Wei, X. Du, L. Du, Q. Wang, W. Zhang, G. Wu, D. Dai, and X. Yang, On-line spectral diagnostic system for Dalian Coherent Light Source, Nucl. Instrum. Methods Phys. Res., Sect. A 783, 65 (2015).
  38. M. Wang, Y. Yu, J. Yang, Q. Li, and W. Zhang, Multi-functional gas cell in the vacuum ultraviolet free-electron laser beamline, Rev. Sci. Instrum. 95, 063101 (2024).
  39. E. Allaria, M. B. Danailov, W. M. Fawley, L. Giannessi, and E. Ferrari, Measurements of the FEL-bandwidth scaling with harmonic number in a HGHG FEL, in Proceedings of the 36th International Free Electron Laser Conference, FEL2014, Basel, Switzerland (JACoW, Geneva, Switzerland, 2014), p. 227.
  40. D. Ratner, A. Fry, G. Stupakov, and W. White, Laser phase errors in seeded free electron lasers, Phys. Rev. ST Accel. Beams 15, 030702 (2012).
  41. C.-Q. Xu et al., Observation of the smallest three-dimensional neutral boron cluster, Angew. Chem., Int. Ed. 64, e202419089 (2025).
  42. Z. Huang and K.-J. Kim, Review of x-ray free-electron laser theory, Phys. Rev. ST Accel. Beams 10, 034801 (2007).
  43. H. Grote and F. C. Iselin, The mad program (methodical accelerator design): Version 8.10; user’s reference manual, Report No. CERN-SL-90-13-AP-Rev-3, CERN, Geneva, 1993.
  44. X. Ming, Design optimization for an x-ray free electron laser driven by SLAC linac, in Proceedings of the Particle Accelerator Conference, Dallas, TX, 1995 (IEEE, New York, 1995), pp. 183.
  45. O. Welz, J. D. Savee, D. L. Osborn, S. S. Vasu, C. J. Percival, D. E. Shallcross, and C. A. Taatjes, Direct kinetic measurements of Criegee intermediate (CH2OO) formed by reaction of CH2I with O2, Science 335, 204 (2012).
  46. K. Yuan, Y. Cheng, L. Cheng, Q. Guo, D. Dai, X. Wang, X. Yang, and R. N. Dixon, Nonadiabatic dissociation dynamics in H2O: Competition between rotationally and nonrotationally mediated pathways, Proc. Natl. Acad. Sci. U.S.A. 105, 19148 (2008).
  47. F. Bridou, M. Cuniot-Ponsard, and J.-M. Desvignes, Experimental determination of optical constants in the vacuum ultra violet wavelength region between 80 and 140 nm: A reflectance versus thickness method and its application to ZnSe, Opt. Commun. 271, 353 (2007).
  48. Y. Chang, M. N. R. Ashfold, K. Yuan, and X. Yang, Exploring the vacuum ultraviolet photochemistry of astrochemically important triatomic molecules, Natl. Sci. Rev. 10, nwad158 (2023).
  49. Y. Chang et al., Tunable VUV photochemistry using vacuum ultraviolet free electron laser combined with H-atom Rydberg tagging time-of-flight spectroscopy, Rev. Sci. Instrum. 89, 063113 (2018).
  50. L. C. Lee and M. Suto, Quantitative photoabsorption and fluorescence study of H2O and D2O at 50–190 nm, Chem. Phys. 110, 161 (1986).
  51. https://cstr.cn/31127.02.DCLS

Outline

Information

Phys. Rev. Accel. Beams 28, 100701– Published 9 October, 2025
  • Received 13 June 2025
  • Accepted 3 September 2025
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation