| 1. |
- Varju, Katalin, et al.
(författare)
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Experimental studies of attosecond pulse trains
- 2005
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Ingår i: Laser Physics. - 1054-660X. ; 15:6, s. 888-898
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental measurements of attosecond pulse trains. The characterization of the pulses uses a spectral interferometry technique that is implemented with a Mach-Zehnder interferometer. This allows us to manipulate independently the pump and probe pulses for a wide range of applications. By letting the attosecond pulses pass through metallic films, we can in particular compensate for the intrinsic chirp of the attosecond pulses corresponding to the plateau spectral region, thus getting pulses as short as 170 attoseconds-only 1.2 optical cycles at the central frequency. The measurement technique is also applicable for determination of the group delay of thin XUV-transparent films and relative delay in the photoionization process. Our experimental method is applied to attosecond pulse trains created by 35- and 9-fs laser pulses, and the shortest train observed consists of three or four pulses.
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| 2. |
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| 3. |
- Sola, I. J., et al.
(författare)
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Temporal and spectral studies of high-order harmonics generated by polarization-modulated infrared fields
- 2006
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 74:1
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Tidskriftsartikel (refereegranskat)abstract
- The temporal confinement of high harmonic generation (HHG) via modulation of the polarization of the fundamental pulse is studied in both temporal and spectral domains. In the temporal domain, a collinear cross-correlation setup using a 40 fs IR pump for the HHG and a 9 fs IR pulse to probe the generated emission is used to measure the XUV pulse duration. The observed temporal confinement is found to be consistent with theoretical predictions. An increased confinement is observed when a 9 fs pulse is used to generate the harmonics. An important spectral broadening, including a continuum background, is also measured. Theoretical calculations show that with 10 fs driving pulses, either one or two main attosecond pulses are created depending on the value of the carrier envelope phase.
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| 4. |
- Zaïr, A., et al.
(författare)
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Confinement of attosecond train pulses by using a modulated polarization IR pulse
- 2005
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Ingår i: 2005 Conference on Lasers and Electro-Optics Europe. - 0780389743 - 9780780389748
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Konferensbidrag (refereegranskat)abstract
- We study the temporal and spectral behaviour of high order harmonics generated by pulses with temporally modulated polarization. We observe a harmonic temporal confinement and a harmonic spectral broadening, compatible with 1 -or-2 attosecond pulse emission.
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| 5. |
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| 6. |
- Carré, B., et al.
(författare)
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Characterization of attosecond pulse trains
- 2007
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Ingår i: Ultrafast Optics V. - New York, NY : Springer New York. - 1556-1534 .- 0342-4111. - 9780387491172 ; 132, s. 45-56
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Konferensbidrag (refereegranskat)abstract
- Ultrashort light pulses, as short as 100 as, can be produced from high harmonic generation (HHG) in an atomic gas medium. This major achievement of the last 6 years in high field physics has now been demonstrated in different conditions of medium-field interaction [1].
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| 7. |
- Hauri, C. P., et al.
(författare)
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Attosecond pulse trains generated in a filament
- 2006
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Ingår i: Quantum Electronics and Laser Science Conference, QELS 2006. - 1557528136 - 9781557528131
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Konferensbidrag (refereegranskat)abstract
- We present temporal characterization of attosecond pulse trains generated during selfguided propagation of intense pulses in a long gas target. Spectral phase jumps are observed, affecting the temporal shape of the attosecond pulse train.
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| 8. |
- Hauri, C. P., et al.
(författare)
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Self-compression of ultrashort pulses in filaments
- 2006
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Ingår i: Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, CLEO/QELS 2006. - 1557528136 - 9781557528131
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Konferensbidrag (refereegranskat)abstract
- We report the self-compression of linearly and circularly polarized light pulses down to the few-cycle regime by self-guided beam propagation of intense 38-fs pulses in different gases with uniform density and with a pressure gradient.
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| 9. |
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| 10. |
- Kelkensberg, F., et al.
(författare)
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Molecular Dissociative Ionization and Wave-Packet Dynamics Studied Using Two-Color XUV and IR Pump-Probe Spectroscopy
- 2009
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Ingår i: Physical Review Letters. - 1079-7114. ; 103:12
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Tidskriftsartikel (refereegranskat)abstract
- We present a combined theoretical and experimental study of ultrafast wave-packet dynamics in the dissociative ionization of H-2 molecules as a result of irradiation with an extreme-ultraviolet (XUV) pulse followed by an infrared (IR) pulse. In experiments where the duration of both the XUV and IR pulses are shorter than the vibrational period of H-2+, dephasing and rephasing of the vibrational wave packet that is formed in H-2+ upon ionization of the neutral molecule by the XUV pulse is observed. In experiments where the duration of the IR pulse exceeds the vibrational period of H-2+ (15 fs), a pronounced dependence of the H+ kinetic energy distribution on XUV-IR delay is observed that can be explained in terms of the adiabatic propagation of the H-2+ wave packet on field-dressed potential energy curves.
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| 11. |
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| 12. |
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| 13. |
- Kovacev, M, et al.
(författare)
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Extreme ultraviolet fourier-transform spectroscopy with high order harmonics
- 2005
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Ingår i: Physical Review Letters. - 1079-7114. ; 95:22
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a new scheme for extreme ultraviolet (xuv) Fourier-transform spectroscopy based on the generation of two phase-locked high-harmonic beams. It allows us to measure for the first time interferograms at wavelengths as short as 90 nm, and open the perspective of performing high-resolution Fourier-transform absorption spectroscopy in the xuv. Our measurements also demonstrate that a precise control of the relative phase of harmonic pulses can be obtained with an accuracy on an attosecond time scale, of importance for future xuv pump-xuv probe attosecond spectroscopy.
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| 14. |
- Lepine, F., et al.
(författare)
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Short XUV pulses to characterize field-free molecular alignment
- 2007
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Ingår i: Journal of Modern Optics. - : Informa UK Limited. - 0950-0340 .- 1362-3044. ; 54:7, s. 953-966
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Tidskriftsartikel (refereegranskat)abstract
- We present experiments on field-free molecular alignment of N-2 and CO2 probed with short XUV pulses that are obtained via high-harmonic generation. The XUV pulses induce a dissociative ionization or a Coulomb explosion of the molecule, where the fragment ion recoil (measured using the velocity map imaging technique) provides information on the alignment of the parent molecule at the time of ionization. We discuss how photoelectron detection may in future allow the determination of molecular-frame photoelectron angular distributions and molecular structure.
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| 15. |
- L'Huillier, A., et al.
(författare)
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Atomic physics with attosecond pulses
- 2006
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Ingår i: International Conference on Ultrafast Phenomena, UP 2006. - 1557528101 - 9781557528100
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Konferensbidrag (refereegranskat)
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| 16. |
- Mansten, Erik, et al.
(författare)
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Broadband attosecond pulse shaping
- 2007
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Ingår i: Optics Letters. - 0146-9592. ; 32:11, s. 1353-1355
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Tidskriftsartikel (refereegranskat)abstract
- We use semiconductor (Si) and metallic (Al, Zr) transmission filters to shape, in amplitude and phase, high-order harmonics generated from the interaction of an intense titanium sapphire laser field with a pulsed neon gas target. Depending on the properties of the filter, the emitted attosecond pulses can be optimized in bandwidth and/or pulse length. We demonstrate the generation of attosecond pulses centered at energies from 50 to 80 eV, with bandwidths as large as 45 eV and with pulse durations compressed to 130 as. (c) 2007 Optical Society of America.
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| 17. |
- Power, E., et al.
(författare)
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Dispersion-free interferometric autocorrelator for measurement of ultra-broadband pulses
- 2006
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Ingår i: Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, CLEO/QELS 2006. - 1557528136 - 9781557528131
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a dispersion-free split mirror interferometric autocorrelator suitable for measuring pulses with durations from hundreds of attoseconds to tens of femtoseconds and spectral content from the near-UV to near-IR.
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| 18. |
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| 19. |
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| 20. |
- Sansone, G., et al.
(författare)
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Attosecond excitation of electron wavepackets
- 2008
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Ingår i: Quantum Electronics and Laser Science Conference, QELS 2008. - 9781557528599
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Konferensbidrag (refereegranskat)abstract
- We present experiments, supported by time-dependent Schrödinger simulations, on the dynamics of Helium bound states after an attosecond excitation in the presence of a strong infrared laser field.
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| 21. |
- Varju, Katalin, et al.
(författare)
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Attosecond dynamics of electron wave packets in intense laser fields
- 2007
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Ingår i: Ultrafast Optics V (Springer Series in Optical Sciences). - 0342-4111. - 9780387491172 ; 132, s. 15-24
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Konferensbidrag (refereegranskat)abstract
- We use a train of sub-200 attosecond extreme ultraviolet (XUV) pulses with energies just above the ionization threshold in argon to create a train of temporally localized electron wave packets. We study the energy transfer from a strong infrared (IR) laser field to the ionized electrons as a function of the delay between the XUV and IR fields. When the wave packets are born at the zero crossings of the IR field, a significant amount of energy (∼20 eV) is transferred from the field to the electrons. This results in dramatically enhanced above-threshold ionization in conditions where the IR field alone does not induce any significant ionization. Because both the energy and duration of the wave packets can be varied independently of the IR laser, they are valuable tools for studying and controlling strong-field processes.
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