High-harmonic generation driven by femtosecond lasers makes it possible to capture the fastest dynamics in molecules and materials. However, thus far, the shortest isolated attosecond pulses have only been produced with linear polarization, which limits the range of physics that can be explored. Here, we demonstrate robust polarization control of isolated extreme-ultraviolet pulses by exploiting non-collinear high-harmonic generation driven by two counter-rotating few-cycle laser beams. The circularly polarized supercontinuum is produced at a central photon energy of 33 eV with a transform limit of 190 as and a predicted linear chirp of 330 as. By adjusting the ellipticity of the two counter-rotating driving pulses simultaneously, we control the polarization state of isolated extreme-ultraviolet pulses—from circular through elliptical to linear polarization—without sacrificing conversion efficiency. Access to the purely circularly polarized supercontinuum, combined with full helicity and ellipticity control, paves the way towards attosecond metrology of circular dichroism.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


  1. 1.

    Spezzani, C. et al. Coherent light with tunable polarization from single-pass free-electron lasers. Phys. Rev. Lett. 107, 084801 (2011).

  2. 2.

    Suzuki, M., Inubushi, Y., Yabashi, M. & Ishikawa, T. Polarization control of an X-ray free-electron laser with a diamond phase retarder. J. Synchrot. Radiat. 21, 466–472 (2014).

  3. 3.

    Lutman, A. A. et al. Polarization control in an X-ray free-electron laser. Nat. Photon. 10, 468–472 (2016).

  4. 4.

    Allaria, E. et al. Control of the polarization of a vacuum-ultraviolet, high-gain, free-electron laser. Phys. Rev. X 4, 041040 (2014).

  5. 5.

    Eichmann, H., Egbert, A., Nolte, S., Momma, C. & Wellegehausen, B. Polarization-dependent high-order two-color mixing. Phys. Rev. A 51, R3414–R3417 (1995).

  6. 6.

    Fleischer, A., Kfir, O., Diskin, T., Sidorenko, P. & Cohen, O. Spin angular momentum and tunable polarization in high-harmonic generation. Nat. Photon. 8, 543–549 (2014).

  7. 7.

    Ferré, A. et al. A table-top ultrashort light source in the extreme ultraviolet for circular dichroism experiments. Nat. Photon. 9, 93–98 (2015).

  8. 8.

    Kfir, O. et al. Generation of bright phase-matched circularly-polarized extreme ultraviolet high harmonics. Nat. Photon. 9, 99–105 (2015).

  9. 9.

    Fan, T. et al. Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism. Proc. Natl Acad. Sci. USA 112, 14206–14211 (2015).

  10. 10.

    Ribic, P. R. & Margaritondo, G. Status and prospects of X-ray free-electron lasers (X-FELs): a simple presentation. J. Phys. D 45, 213001 (2012).

  11. 11.

    Schafer, K. J., Yang, B., DiMauro, L. F. & Kulander, K. C. Above threshold ionization beyond the high harmonic cutoff. Phys. Rev. Lett. 70, 1599–1602 (1993).

  12. 12.

    Corkum, P. B. Plasma perspective on strong-field multiphoton ionization. Phys. Rev. Lett. 71, 1994–1997 (1993).

  13. 13.

    Balcou, P., Salieres, P., L’Huillier, A. & Lewenstein, M. Generalized phase-matching conditions for high harmonics: the role of field-gradient forces. Phys. Rev. A 55, 3204–3210 (1997).

  14. 14.

    Rundquist, A. et al. Phase-matched generation of coherent soft X-rays. Science 280, 1412–1415 (1998).

  15. 15.

    Gaarde, M. B., Tate, J. L. & Schafer, K. J. Macroscopic aspects of attosecond pulse generation. J. Phys. B 41, 132001 (2008).

  16. 16.

    Arpin, P., Murnane, M. M. & Kapteyn, H. C. Quasi-phase-matching of momentum and energy in nonlinear optical processes. Nat. Photon. 4, 571–575 (2010).

  17. 17.

    Sun, H.-W. et al. Extended phase matching of high harmonic generation by plasma-induced defocusing. Optica 4, 976–981 (2017).

  18. 18.

    Dietrich, P., Burnett, N. H., Ivanov, M. & Corkum, P. B. High-harmonic generation and correlated two-electron multiphoton ionization with elliptically polarized light. Phys. Rev. A 50, R3585–R3588 (1994).

  19. 19.

    Weihe, F. A. et al. Polarization of high-intensity high-harmonic generation. Phys. Rev. A 51, R3433–R3436 (1995).

  20. 20.

    Vodungbo, B. et al. Polarization control of high order harmonics in the EUV photon energy range. Opt. Express 19, 4346–4356 (2011).

  21. 21.

    Medišauskas, L., Wragg, J., van der Hart, H. & Ivanov, M. Y. Generating isolated elliptically polarized attosecond pulses using bichromatic counterrotating circularly polarized laser fields. Phys. Rev. Lett. 115, 153001 (2015).

  22. 22.

    Hickstein, D. D. et al. Non-collinear generation of angularly isolated circularly polarized high harmonics. Nat. Photon. 9, 743–750 (2015).

  23. 23.

    Hernandez-Garcia, C. et al. Schemes for generation of isolated attosecond pulses of pure circular polarization. Phys. Rev. A 93, 043855 (2016).

  24. 24.

    Lu, C.-H. et al. Generation of intense supercontinuum in condensed media. Optica 1, 400–406 (2014).

  25. 25.

    Chen, M.-C. et al. Generation of bright isolated attosecond soft X-ray pulses driven by multicycle midinfrared lasers. Proc. Natl Acad. Sci. USA 111, E2361–E2367 (2014).

  26. 26.

    Hernández-García, C., San Román, J., Plaja, L. & Picón, A. Quantum-path signatures in attosecond helical beams driven by optical vortices. New. J. Phys. 17, 093029 (2015).

  27. 27.

    Rego, L., San Román, J., Picón, A., Plaja, L. & Hernández-García, C. Nonperturbative twist in the generation of extreme-ultraviolet vortex beams. Phys. Rev. Lett. 117, 163202 (2016).

  28. 28.

    Trebino, R. et al. Measuring ultrashort laser pulses in the time-frequency domain using frequency-resolved optical gating. Rev. Sci. Instrum. 68, 3277–3295 (1997).

  29. 29.

    Heyl, C. M. et al. Noncollinear optical gating. New. J. Phys. 16, 052001 (2014).

  30. 30.

    Koide, T. et al. Elliptical-polarization analyses of synchrotron radiation in the 5–80-eV region with a reflection polarimeter. Nucl. Instrum. Methods Phys. Rec. Sect. A 308, 635–644 (1991).

  31. 31.

    Hernández-García, C. et al. High-order harmonic propagation in gases within the discrete dipole approximation. Phys. Rev. A 82, 033432 (2010).

  32. 32.

    Xie, X. et al. Internal momentum state mapping using high harmonic radiation. Phys. Rev. Lett. 101, 033901 (2008).

  33. 33.

    Zhou, X. et al. Elliptically polarized high-order harmonic emission from molecules in linearly polarized laser fields. Phys. Rev. Lett. 102, 073902 (2009).

  34. 34.

    Fleischer, A., Sidorenko, P. & Cohen, O. Generation of high-order harmonics with controllable elliptical polarization. Opt. Lett. 38, 223–225 (2013).

  35. 35.

    Dorney, K. M. et al. Helicity-selective enhancement and polarization control of attosecond high harmonic waveforms driven by bichromatic circularly polarized laser fields. Phys. Rev. Lett. 119, 063201 (2017).

  36. 36.

    Chini, M., Zhao, K. & Chang, Z. The generation, characterization and applications of broadband isolated attosecond pulses. Nat. Photon. 8, 178–186 (2014).

  37. 37.

    Stöhr, J. et al. Element-specific magnetic microscopy with circularly polarized X-rays. Science 259, 658–661 (1993).

  38. 38.

    Boeglin, C. et al. Distinguishing the ultrafast dynamics of spin and orbital moments in solids. Nature 465, 458–461 (2010).

  39. 39.

    Meyer-Ilse, J., Akimov, D. & Dietzek, B. Recent advances in ultrafast time-resolved chirality measurements: perspective and outlook. Laser Photon. Rev. 7, 495–505 (2013).

  40. 40.

    Graves, C. E. Nanoscale spin reversal by non-local angular momentum transfer following ultrafast laser excitation in ferrimagnetic GdFeCo. Nat. Mater. 12, 293–298 (2013).

  41. 41.

    Chefdeville, S. et al. Direct determination of absolute molecular stereochemistry in gas phase by Coulomb explosion imaging. Science 341, 1094–1096 (2013).

  42. 42.

    Bigot, J.-Y., Vomir, M. & Beaurepaire, E. Coherent ultrafast magnetism induced by femtosecond laser pulses. Nat. Phys. 5, 515–520 (2009).

  43. 43.

    Mangot, L. et al. Broadband transient dichroism spectroscopy in chiral molecules. Opt. Lett. 35, 381–383 (2010).

  44. 44.

    Janssen, M. H. & Powis, I. Detecting chirality in molecules by imaging photoelectron circular dichroism. Phys. Chem. Chem. Phys. 16, 856–871 (2014).

  45. 45.

    Cireasa, R. et al. Probing molecular chirality on a sub-femtosecond timescale. Nat. Phys. 11, 654–658 (2015).

  46. 46.

    Tao, Z. et al. Direct time-domain observation of attosecond final-state lifetimes in photoemission from solids. Science 353, 62–67 (2016).

  47. 47.

    Fidler, A. F., Singh, V. P., Long, P. D., Dahlberg, P. D. & Engel, G. S. Dynamic localization of electronic excitation in photosynthetic complexes revealed with chiral two-dimensional spectroscopy. Nat. Commun. 5, 3286 (2017).

  48. 48.

    Chen, C. et al. Distinguishing attosecond electron–electron scattering and screening in transition metals. Proc. Natl Acad. Sci. USA 114, E5300–E5307 (2017).

  49. 49.

    Beaulieu, S. et al. Probing ultrafast dynamics of chiral molecules using time-resolved photoelectron circular dichroism. Faraday Discuss. 194, 325–348 (2016).

Download references


The experimental work was carried out at National Tsing Hua University, Institute of Photonics Technologies, supported by the Ministry of Science and Technology, Taiwan (grants 105-2112-M-007-030-MY3, 105-2112-M-001-030 and 104-2112-M-007-012-MY3). The concept of isolated circularly polarized attosecond pulses was developed by C.H.-G., D.D.H., M.M.M., C.G.D., H.C.K., A.B. and A.J.-B.. C.H.-G. acknowledges support from the Marie Curie International Outgoing Fellowship within the EU Seventh Framework Programme for Research and Technological Development (2007–2013), under Research Executive Agency grant agreement no. 328334. C.H.-G. and L.P. acknowledge support from Junta de Castilla y León (SA046U16) and the Ministerio de Economía y Competitividad (FIS2013-44174-P, FIS2016-75652-P). C.H.-G. acknowledges support from a 2017 Leonardo Grant for Researchers and Cultural Creators (BBVA Foundation). M.M.M. and H.C.K. acknowledge support from the Department of Energy Basic Energy Sciences (award no. DE-FG02-99ER14982) for the concepts and experimental set-up. For part of the theory, A.B., A.J.-B., C.G.D., M.M.M. and H.C.K. acknowledge support from a Multidisciplinary University Research Initiatives grant from the Air Force Office of Scientific Research (award no. FA9550-16-1-0121). A.J.-B. also acknowledges support from the US National Science Foundation (grant no. PHY-1734006). This work utilized the Janus supercomputer, which is supported by the US National Science Foundation (grant no. CNS-0821794) and the University of Colorado, Boulder. This research made use of the high-performance computing resources of the Castilla y León Supercomputing Center (SCAYLE, www.scayle.es), financed by the European Regional Development Fund (ERDF). J.L.E. acknowledges support from the National Science Foundation Graduate Research Fellowship (DGE-1144083). L.R. acknowledges support from the Ministerio de Educación, Cultura y Deporte (FPU16/02591).

Author information


  1. Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan

    • Pei-Chi Huang
    • , Jen-Ting Huang
    • , Po-Yao Huang
    • , Chih-Hsuan Lu
    • , Shang-Da Yang
    • , A. H. Kung
    •  & Ming-Chang Chen
  2. Institute of Atomic and Molecular Sciences, Academica Sinica, Taipei, Taiwan

    • Pei-Chi Huang
    • , Chih-Hsuan Lu
    •  & A. H. Kung
  3. Grupo de Investigación en Aplicaciones del Láser y Fotónica, Departamento de Física Aplicada, University of Salamanca, Salamanca, Spain

    • Carlos Hernández-García
    • , Laura Rego
    •  & Luis Plaja
  4. JILA – Department of Physics, University of Colorado and NIST, Boulder, CO, USA

    • Daniel D. Hickstein
    • , Jennifer L. Ellis
    • , Agnieszka Jaron-Becker
    • , Andreas Becker
    • , Henry C. Kapteyn
    •  & Margaret M. Murnane
  5. Department of Physics, Colorado School of Mines, Golden, CO, USA

    • Charles G. Durfee
  6. Department of Physics, National Tsing Hua University, Hsinchu, Taiwan

    • Ming-Chang Chen


  1. Search for Pei-Chi Huang in:

  2. Search for Carlos Hernández-García in:

  3. Search for Jen-Ting Huang in:

  4. Search for Po-Yao Huang in:

  5. Search for Chih-Hsuan Lu in:

  6. Search for Laura Rego in:

  7. Search for Daniel D. Hickstein in:

  8. Search for Jennifer L. Ellis in:

  9. Search for Agnieszka Jaron-Becker in:

  10. Search for Andreas Becker in:

  11. Search for Shang-Da Yang in:

  12. Search for Charles G. Durfee in:

  13. Search for Luis Plaja in:

  14. Search for Henry C. Kapteyn in:

  15. Search for Margaret M. Murnane in:

  16. Search for A. H. Kung in:

  17. Search for Ming-Chang Chen in:


P.-C.H., J.-T.H., P.-Y.H., C.-H.L., D.D.H., J.L.E., C.G.D., H.C.K., M.M.M., A.H.K. and M.-C.C. designed the experiment with circularly polarized isolated high-harmonic pulses. P.-C.H., J.-T.H., P.-Y.H., S.-D.Y., A.H.K. and M.-C.C. proposed the full polarization control of HHG and designed the EUV polarimeter. P.-C.H., J.-T.H., P.-Y.H., C.-H.L. and M.-C.C. performed the experiments. C.H.-G., A.B. and A.J.-B. performed the theoretical simulations on circularly polarized isolated attosecond pulses. C.H.-G., L.R. and L.P. worked on the theoretical methods and simulations of the full polarization control of HHG. P.-C.H., C.H.-G., J.-T.H., P.-Y.H., L.R., L.P. and M.-C.C. analysed data. P.-C.H., C.H.-G., L.P., M.M.M. and M.-C.C. wrote the manuscript, to which all authors suggested improvement.

Competing interests

The authors declare no competing interests.

Corresponding authors

Correspondence to Pei-Chi Huang or Ming-Chang Chen.

Supplementary information

  1. Supplementary Information

    Supplementary notes, figures and table

  2. Supplementary Video 1

    Interference patterns of circularly polarized extreme-ultraviolet pulses versus time delays.

About this article

Publication history