Monday, July 20, 2015

Abstract-High density terahertz frequency comb produced by coherent synchrotron radiation

  • S. Tammaro,
  • O. Pirali,
  • P. Roy,
  • J.-F. Lampin,
  • G. Ducournau,
  • A. Cuisset,
  • F. Hindle

  • G. Mouret

    Frequency combs have enabled significant progress in frequency metrology and high-resolution spectroscopy extending the achievable resolution while increasing the signal-to-noise ratio. In its coherent mode, synchrotron radiation is accepted to provide an intense terahertz continuum covering a wide spectral range from about 0.1 to 1THz. Using a dedicated heterodyne receiver, we reveal the purely discrete nature of this emission. A phase relationship between the light pulses leads to a powerful frequency comb spanning over one decade in frequency. The comb has a mode spacing of 846kHz, a linewidth of about 200Hz, a fractional precision of about 2 × 10−10 and no frequency offset. The unprecedented potential of the comb for high-resolution spectroscopy is demonstrated by the accurate determination of pure rotation transitions of acetonitrile.

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