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Bright High-Repetition-Rate XUV Source for Ultrafast ARPES

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XUV source scheme with spectra & isolated 22 eV harmonic.

Scientific Achievement
Demonstrated a highly-efficient XUV source for Time- & Angle-Resolved Photoemission Spectroscopy (trARPES) that delivers spectrally-isolated 22 eV pulses, uniquely combining 50-kHz repetition rate, narrow bandwidth, and high sample flux.

Significance and Impact
The XUV source enables studies of electronic dynamics in materials with high sensitivity, energy resolution & momentum-space access.

Research Details

  • A bright XUV flux is obtained in a cascaded scheme, with ultraviolet pulses focused tightly into Kr gas
  • The conversion efficiency exceeds directly-driven harmonics more than 100-fold, boosted by dipole scaling & enhanced phase-matching
  • A single 22 eV harmonic is directly isolated via metal foils, without needing a complex monochromator

H. Wang, Y. Xu, S. Ulonska, J. S. Robinson, P. Ranitovic & R. A. Kaindl, “Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV” – Nature Communications 6, 7459 (2015).