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Direct observation of attosecond light bunching


Temporal probing of a number of fundamental dynamical processes requires intense pulses at femtosecond or even attosecond (1 as = 10-18 s) timescales. A frequency ‘comb’ of extreme-ultraviolet odd harmonics can easily be generated in the interaction of subpicosecond laser pulses with rare gases: if the spectral components within this comb possess an appropriate phase relationship to one another, their Fourier synthesis results in an attosecond pulse train1,2. Laser pulses spanning many optical cycles have been used for the production of such light bunching3,4, but in the limit of few-cycle pulses the same process produces isolated attosecond bursts5,6. If these bursts are intense enough to induce a nonlinear process in a target system7,8,9, they can be used for subfemtosecond pump–probe studies of ultrafast processes. To date, all methods for the quantitative investigation of attosecond light localization4,6,10 and ultrafast dynamics11 rely on modelling of the cross-correlation process between the extreme-ultraviolet pulses and the fundamental laser field used in their generation. Here we report the direct determination of the temporal characteristics of pulses in the subfemtosecond regime, by measuring the second-order autocorrelation trace of a train of attosecond pulses. The method exhibits distinct capabilities for the characterization and utilization of attosecond pulses for a host of applications in attoscience.

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Figure 1: The second-order XUV autocorrelator.
Figure 2: Ion yield dependence on the XUV radiation.
Figure 3: Measured nonlinear volume autocorrelation traces.


  1. Hänsch, T. W. A proposed sub-femtosecond pulse synthesizer using separate phase-locked laser oscillators. Opt. Commun. 80, 71–75 (1990)

    Article  ADS  Google Scholar 

  2. Farkas, Gy & Tóth, Cs Proposal for attosecond light pulse generation using laser induced multiple-harmonic conversion processes in rare gases. Phys. Lett. A 168, 447–450 (1992)

    Article  ADS  CAS  Google Scholar 

  3. Papadogiannis, N. A., Witzel, B., Kalpouzos, C. & Charalambidis, D. Observation of attosecond light localization in higher order harmonic generation. Phys. Rev. Lett. 83, 4289–4292 (1999)

    Article  ADS  CAS  Google Scholar 

  4. Paul, P. M. et al. Observation of a train of attosecond pulses from high harmonic generation. Science 292, 1689–1692 (2001)

    Article  ADS  CAS  Google Scholar 

  5. Christov, I. P., Murnane, M. M. & Kapteyn, H. High-harmonic generation of attosecond pulses in the “single-cycle” regime. Phys. Rev. Lett. 78, 1251–1254 (1997)

    Article  ADS  CAS  Google Scholar 

  6. Hentschel, M. et al. Attosecond metrology. Nature 414, 509–513 (2001)

    Article  ADS  CAS  Google Scholar 

  7. Kobayashi, Y., Sekikawa, T., Nabekawa, Y. & Watanabe, S. 27-fs extreme ultraviolet pulse generation by high-order harmonics. Opt. Lett. 23, 64–66 (1998)

    Article  ADS  CAS  Google Scholar 

  8. Papadogiannis, N. A. et al. Two XUV-photon ionization of He through a superposition of higher harmonics. Phys. Rev. Lett. 90, 133902 (2003)

    Article  ADS  CAS  Google Scholar 

  9. Papadogiannis, N. A. et al. On the feasibility of performing non-linear autocorrelation with attosecond pulse trains. Appl. Phys. B 76, 721–727 (2003)

    Article  ADS  CAS  Google Scholar 

  10. Kienberger, R. et al. Steering attosecond electron wave packets with light. Science 297, 1144–1148 (2002)

    Article  ADS  CAS  Google Scholar 

  11. Drescher, M. et al. Time-resolved atomic inner-shell spectroscopy. Nature 419, 803–807 (2002)

    Article  ADS  CAS  Google Scholar 

  12. Steinmeyer, G., Sutter, D., Gallmann, L., Matuschek, N. & Keller, U. Frontiers in ultrashort pulse generation: pushing the limits in linear and nonlinear optics. Science 286, 1507–1512 (1999)

    Article  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

  14. Lewenstein, M., Balcou, Ph., Ivanov, M. Yu., L'Huillier, A. & Corkum, P. B. Theory of high-harmonic generation by low-frequency laser fields. Phys. Rev. A 49, 2117–2132 (1994)

    Article  ADS  CAS  Google Scholar 

  15. Salières, P. et al. Feyman's path-integral approach for intense-laser-atom interactions. Science 292, 902–905 (2001)

    Article  ADS  Google Scholar 

  16. Chang, Z. et al. Temporal phase control of soft-x-ray harmonic emission. Phys. Rev. A 58, R30–R33 (1998)

    Article  ADS  CAS  Google Scholar 

  17. Gaarde, M. B. et al. Spatiotemporal separation of high harmonic radiation into two quantum path components. Phys. Rev. A 59, 1367–1373 (1999)

    Article  ADS  CAS  Google Scholar 

  18. Shin, H. J. et al. Nonadiabatic blueshift of high-order harmonics from Ar and Ne atoms in an intense femtosecond laser field. Phys. Rev. A 63, 053407 (2001)

    Article  ADS  Google Scholar 

  19. Bartels, R. et al. Shaped-pulse optimization of coherent emission of high-harmonic soft X-rays. Nature 406, 164–166 (2000)

    Article  ADS  CAS  Google Scholar 

  20. Christov, I. P., Bartels, R., Kapteyn, H. C. & Murnane, M. M. Attosecond time-scale intra-atomic phase matching of high harmonic generation. Phys. Rev. Lett. 86, 5458–5461 (2001)

    Article  ADS  CAS  Google Scholar 

  21. Papadogiannis, N. A. et al. Temporal characterization of short pulse third-harmonic generation in an atomic gas by a transmission grating Michelson interferometer. Opt. Lett. 27, 1561–1563 (2002)

    Article  ADS  CAS  Google Scholar 

  22. Wabnitz, H. et al. Multiple ionization of atom clusters by intense soft X-rays from a free-electron laser. Nature 420, 482–485 (2002)

    Article  ADS  CAS  Google Scholar 

  23. Peatross, J., Chaloupka, J. L. & Meyerhofer, D. D. High-order harmonic-generation with an annular laser beam. Opt. Lett. 19, 942–944 (1994)

    Article  ADS  CAS  Google Scholar 

  24. Gaarde, M. B. & Schafer, K. J. Space-time considerations in the phase locking of high harmonics. Phys. Rev. Lett. 89, 213901 (2002)

    Article  ADS  Google Scholar 

  25. Constant, E., Mével, E., Zaÿr, A., Bagnoud, V. & Salin, F. Toward sub-femtosecond pump–probe experiments: A dispersionless autocorrelator with attosecond resolution. J. Phys. IV Fr. 11, Pr2-537–Pr2-540 (2001)

    Article  Google Scholar 

  26. Mashiko, H., Suda, A. & Midorikawa, K. All-reflective interferometric autocorrelator for the measurement of ultra-short optical pulses. Appl. Phys. B 76, 525–530 (2003)

    Article  ADS  CAS  Google Scholar 

  27. Sekikawa, T., Katsura, T., Miura, S. & Watanabe, S. Measurement of the intensity-dependent atomic dipole phase of a high harmonic by frequency-resolved optical gating. Phys. Rev. Lett. 88, 193902 (2002)

    Article  ADS  Google Scholar 

  28. Muller, H. G. Reconstruction of attosecond harmonic beating by interference of two-photon transitions. Appl. Phys. B 74 (suppl.), S17–S21 (2002)

    Article  ADS  CAS  Google Scholar 

  29. Quéré, F., Itatani, J., Yudin, G. L. & Corkum, P. B. Attosecond spectral shearing interferometry. Phys. Rev. Lett. 90, 073902 (2003)

    Article  ADS  Google Scholar 

  30. Norin, J. et al. Time-frequency characterization of femtosecond extreme ultraviolet pulses. Phys. Rev. Lett. 88, 193901 (2002)

    Article  ADS  CAS  Google Scholar 

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The experiment was performed using the ATLAS laser facility at the Max-Planck-Institut für Quantenoptik, Garching. This work is supported in part by the European Community's Human Potential Programmes, Generation and Characterisation of Attosecond Pulses in Strong Laser-Atom Interactions: A Step towards Attophysics (ATTO) and the Ultraviolet Laser Facility (ULF).

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Correspondence to G. D. Tsakiris.

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Tzallas, P., Charalambidis, D., Papadogiannis, N. et al. Direct observation of attosecond light bunching. Nature 426, 267–271 (2003).

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