Temporal Coherence of Ultrashort High-Order Harmonic Pulses

M. Bellini; C. Lyngå; A. Tozzi; M. B. Gaarde; T. W. Hänsch; A. L'Huillier; C.-G. Wahlström

doi:10.1103/PhysRevLett.81.297

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Temporal Coherence of Ultrashort High-Order Harmonic Pulses

M. Bellini, C. Lyngå, A. Tozzi, M. B. Gaarde, T. W. Hänsch, A. L'Huillier, and C.-G. Wahlström

Phys. Rev. Lett. 81, 297 – Published 13 July 1998

Abstract

We have studied the temporal coherence of high-order harmonics (up to the 15th order) produced by focusing 100 fs laser pulses into an argon gas jet. We measure the visibility of the interference fringes, produced when two spatially separated harmonic sources interfere in the far field, as a function of the time delay between the two sources. In general, we find long coherence times, comparable to the expected pulse durations of the harmonics. For some of the harmonics, the interference pattern exhibits two regions, with significantly different coherence times. These results are interpreted in terms of different electronic trajectories contributing to harmonic generation.

Received 19 December 1997

DOI:https://doi.org/10.1103/PhysRevLett.81.297

Authors & Affiliations

M. Bellini^1,2, C. Lyngå³, A. Tozzi⁴, M. B. Gaarde^3,5, T. W. Hänsch^2,4,6, A. L'Huillier³, and C.-G. Wahlström³

¹European Laboratory for Non Linear Spectroscopy (L.E.N.S.), Largo E. Fermi, 2, I-50125 Florence, Italy
²Istituto Nazionale di Fisica della Materia, INFM, Florence, Italy
³Department of Physics, Lund Institute of Technology, P.O. Box 118, S-221 00 Lund, Sweden
⁴Department of Physics, University of Florence, Largo E. Fermi, 2, I-50125 Florence, Italy
⁵Niels Bohr Institute, Ørsted Laboratory, 2100 Copenhagen, Denmark
⁶Max-Planck-Institut für Quantenoptik, P.O. Box 1513, D-85740 Garching, Germany