Mode locking in a free-electron laser amplifier

N R Thompson, B W J McNeil

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128 Citations (Scopus)
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A technique is proposed to generate attosecond pulse trains of radiation from a free-electron laser amplifier. The optics-free technique synthesizes a comb of longitudinal modes by applying a series of spatiotemporal shifts between the copropagating radiation and electron bunch in the free-electron laser. The modes may be phase locked by modulating the electron beam energy at the mode spacing frequency. Three-dimensional simulations demonstrate the generation of a train of 400 as pulses at gigawatt power levels evenly spaced by 2.5 fs at a wavelength of 124 A. In the x-ray at wavelength 1.5 A, trains of 23 as pulses evenly spaced by 150 as and of peak power up to 6 GW are predicted.
Original languageEnglish
Article number203901
Number of pages4
JournalPhysical Review Letters
Issue number20
Publication statusPublished - 21 May 2008


  • optical klystron
  • pulses
  • fel
  • free-electron laser
  • mode locking


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