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Title: Echo-enabled harmonics up to the 75th order from precisely tailored electron beams

The production of coherent radiation at ever shorter wavelengths has been a long-standing challenge since the invention of lasers1, 2 and the subsequent demonstration of frequency doubling3. Modern X-ray free-electron lasers (FELs) use relativistic electrons to produce intense X-ray pulses on few-femtosecond timescales4, 5, 6. However, the shot noise that seeds the amplification produces pulses with a noisy spectrum and limited temporal coherence. To produce stable transform-limited pulses, a seeding scheme called echo-enabled harmonic generation (EEHG) has been proposed7, 8, which harnesses the highly nonlinear phase mixing of the celebrated echo phenomenon9 to generate coherent harmonic density modulations in the electron beam with conventional lasers. Here, we report on a demonstration of EEHG up to the 75th harmonic, where 32 nm light is produced from a 2,400 nm laser. We also demonstrate that individual harmonic amplitudes are controlled by simple adjustment of the phase mixing. Results show the potential of laser-based manipulations to achieve precise control over the coherent spectrum in future X-ray FELs for new science10, 11.
Authors:
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Publication Date:
OSTI Identifier:
1260040
Report Number(s):
SLAC-PUB--16547
Journal ID: ISSN 1749-4885
DOE Contract Number:
AC02-76SF00515
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Photonics; Journal Volume: 10; Journal Issue: 8
Publisher:
Nature Publishing Group
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS Accelerators; ACCPHY; PHYS; XFEL