Vacuum ultraviolet frequency combs generated by a femtosecond enhancement cavity in the visible

Birgitta Bernhardt, Akira Ozawa, Andreas Vernaleken, Ioachim Pupeza, Jan Kaster, Yohei Kobayashi, Ronald Holzwarth, Ernst Fill, Ferenc Krausz, Theodor W. Hänsch, Thomas Udem

Research output: Contribution to journalArticlepeer-review


We present the first (to our best knowledge) femtosecond enhancement cavity in the visible wavelength range for ultraviolet frequency comb generation. The cavity is seeded at 518 nm by a frequency-doubled Yb fiber laser and operates at a peak intensity of 1.2texttimes1013  W/cm2. High harmonics of up to the ninth order ($57  nm) are generated in an intracavity xenon gas jet. Intracavity high harmonic powers of several milliwatts for the third harmonic order and microwatts for the fifth harmonic order prove the potential of the ``green cavity'' as an efficient ultraviolet frequency comb source for future spectroscopic experiments. A limiting degradation effect of the cavity mirrors is avoided by operating at a constant oxygen background pressure.
Original languageEnglish
Pages (from-to)503-505
Number of pages3
JournalOptics Letters
Issue number4
Publication statusPublished - 1 Feb 2012
Externally publishedYes


  • Ultrafast lasers
  • UV, EUV, and X-ray lasers
  • Multiharmonic generation
  • High power fiber lasers
  • High power lasers
  • Infrared lasers
  • Infrared radiation
  • Laser sources
  • Pulsed fiber lasers

Fields of Expertise

  • Advanced Materials Science

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