• An Erratum to this article was published on 29 January 2016

This article has been updated


We generate angularly isolated beams of circularly polarized extreme ultraviolet light through the first implementation of non-collinear high harmonic generation with circularly polarized driving lasers. This non-collinear technique offers numerous advantages over previous methods, including the generation of higher photon energies, the separation of the harmonics from the pump beam, the production of both left and right circularly polarized harmonics at the same wavelength and the capability of separating the harmonics without using a spectrometer. To confirm the circular polarization of the beams and to demonstrate the practicality of this new light source, we measure the magnetic circular dichroism of a 20 nm iron film. Furthermore, we explain the mechanisms of non-collinear high harmonic generation using analytical descriptions in both the photon and wave models. Advanced numerical simulations indicate that this non-collinear mixing enables the generation of isolated attosecond pulses with circular polarization.

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Change history

  • 07 October 2015

    In the version of this Article originally published the arrows in Fig. 1b indicating the direction of circular polarization were incorrect and several equations contained typographical errors and should have contained tan functions. These errors have been corrected in all versions of the Article.

  • 15 December 2015

    In the version of this Article originally published the blue dashed line was mislabelled in the legend in Fig. 3d and the label should have read iEvert. This has now been corrected in the online versions of the Article.


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This work was completed at JILA. D.H., J.E., T.F., K.D., H.C. and M.M. acknowledge support from the Department of Energy BES Award DE-FG02-99ER14982. M.M., H.K. and C.D. acknowledge support from the National Science Foundation’s Engineering Research Centre in Extreme Ultraviolet Science and Technology. C.D. acknowledges support from the Air Force Office of Scientific Research under MURI grant FA9550-10-1-0561. J.E. acknowledges support from the National Science Foundation Graduate Research Fellowship (DGE-1144083). C.H.-G. acknowledges support from a Marie Curie International Outgoing Fellowship within the EU Seventh Framework Programme for Research and Technological Development (2007–2013), under REA grant agreement no. 328334. C. H.-G. acknowledges support from Junta de Castilla y León (Project SA116U13) and MINECO (FIS2013-44174-P). A.J.-B. was supported by grants from theNational Science Foundation (grants nos. PHY-1125844 and PHY-1068706). This work made use of the Janus supercomputer, which is supported by the National Science Foundation (award no. CNS-0821794) and the University of Colorado, Boulder. P.G. acknowledges support from the Deutsche Forschungsgemeinschaft (grant no. GR 4234/1–1). R.K. acknowledges the Swedish Research Council (VR) for financial support. A.B. acknowledges support from the Department of Energy, Office of Basic Sciences.

Author information


  1. JILA – Department of Physics, University of Colorado and NIST, Boulder, Colorado 80309, USA

    • Daniel D. Hickstein
    • , Franklin J. Dollar
    • , Patrik Grychtol
    • , Jennifer L. Ellis
    • , Ronny Knut
    • , Carlos Hernández-García
    • , Dmitriy Zusin
    • , Christian Gentry
    • , Tingting Fan
    • , Kevin M. Dorney
    • , Andreas Becker
    • , Agnieszka Jaroń-Becker
    • , Henry C. Kapteyn
    • , Margaret M. Murnane
    •  & Charles G. Durfee
  2. Grupo de Investigación en Óptica Extrema, Universidad de Salamanca, Salamanca E-37008, Spain

    • Carlos Hernández-García
  3. Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado 80305, USA

    • Justin M. Shaw
  4. Department of Physics, Colorado School of Mines, Golden, Colorado 80401, USA

    • Charles G. Durfee


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C.D., D.H., F.D., M.M. and H.K. conceived the NCP-HHG experiment. P.G., R.K., D.Z. and C.G. designed the MCD experiment. J.S. fabricated and characterized the magnetic sample. D.H., F.D., J.E., K.D., P.G., R.K., D.Z., C.G. and T.F. conducted the experiments. C.H.-G., C.D., A.J.-B. and A.B. conducted and interpreted the numerical simulations of HHG, including propagation. D.H., C.D., F.D., P.G., M.M., H.K. and C.H.-G. wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Daniel D. Hickstein.

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