Direct Measurement of the XUV Frequency Comb Coherence

ORAL

Abstract

We present the first demonstration of XUV radiation with phase coherence capable of reaching sub-kHz resolution. The XUV comb is produced by frequency up conversion of a near-infrared frequency comb by intra-cavity high harmonic generation (HHG). Using an 80 W Yb:fiber fs frequency comb, we simultaneously pump two femtosecond enhancement cavities to reach intensities suitable for HHG. The harmonics are out-coupled from the cavities using sapphire plates placed at Brewster angle for the pump laser. We developed an interferometer capable of operating in the XUV and measured a heterodyne beat between the two sources at different harmonics. Despite being insensitive to common-mode pump laser noise, the heterodyne beats will reveal any noise added by the intra-cavity HHG process. This will allow us to probe the fundamental limit on the coherence properties of HHG.

*We acknowledge support for this work from NIST, AFOSR, and NSF

–

Authors

  • Craig Benko

    • JILA, NIST, University of Colorado, Boulder

  • Thomas K. Allison

    • JILA, NIST, University of Colorado, Boulder

  • Arman Cingoz

    • JILA, NIST, University of Colorado, Boulder

  • Dylan C. Yost

    • JILA, NIST, University of Colorado, Boulder

  • Jun Ye

    • JILA, NIST, University of Colorado, Boulder
    • JILA, National Institute of Standards and Technology and University of Colorado, Department of Physics, University of Colorado, Boulder, CO 80309, USA
    • JILA/University of Colorado at Boulder
    • JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, CO
    • JILA, University of CO, Boulder and NIST
    • JILA, NIST and University of Colorado-Boulder, and Department of Physics, University of Colorado-Boulder
    • JILA, National Institute of Standards and Technology and University of Colorado, Department of Physics
    • JILA, NIST, and University of Colorado-Boulder