题目：Methods of isolated attosecond pulse production
报告人：Vasily V. Strelkov (Senior Scientific Researcher)
单位：俄罗斯科学院普通物理研究所
时间：10月29日（星期五）上午9:30
地点：缘园 溢智厅
报告摘要：
The broad envelope spectrum of high harmonics of intense laser radiation generated in gases implies that appropriate phase locking of different harmonics can result in a train of very short pulses of attosecond (1as=10-18s) duration. Obtaining a “single” attosecond pulse remains an important problem.
In our paper we discuss several ways that could be used to solve this problem. In this connection theoretical approaches to microscopic and macroscopic harmonic response calculation are presented.
The first way to obtain a single attosecond pulse is to use very short (few-cycles) linearly polarized laser pulse such that the emission of the high harmonics is naturally confined to a fraction of the laser oscillation period at the peak of the pulse. The second way is to generate harmonics with a pulse whose polarization changes with time. High harmonic generation (HHG) is extremely sensitive to the ellipticity of the fundamental field and typically a 10%–15% ellipticity reduces the generation efficiency by a factor of two. Therefore, under temporal modulation of the fundamental ellipticity the harmonic emission is confined inside the temporal “gate” where the polarization is close to linear. If this “gate” is short enough one could obtain an emission of a single attosecond pulse. An advantage of this method is that one could achieve single attosecond pulse generation using longer fundamental pulse than one is required in the first method. Besides, using a fundamental with a time-modulated ellipticity provides a temporal confinement of all high harmonics, i.e., both plateau and cut-off ones. The third way is based on the transient phase-matching of the harmonic generation. The HHG phase-matching in gases is very sensitive to the free-electronic density in the medium. Ionization necessarily accompanies HHG, thus the phase-matching conditions vary during the laser pulse. The time-dependent phase-matching can limit the duration of the attosecond pulse train obtained from a group of harmonics. If the temporal window of the phase-matched XUV generation is shorter than the laser half-cycle, a single attopulse can be obtained. This method could provide high energy of the generated isolated attosecond pulse.
报告人简介：
2009 Habituation, General Physics Institute of Russian Academy of Sciences, Moscow, Russia
* * Title: “Attosecond pulses generation with intense laser field in gaseous media”
2000 Ph.D. (Laser Physics)
Moscow State University, Russia
* * Thesis title: “High-order harmonics generation in a high-intensity laser field and problem of phase-matching”
* * Professor: Viktor T. Platonenko
1997 B.Sc. / M.Sc. Diploma cum Laude (Laser Physics)
Moscow State University, Physics Department, Chair of General Physics and Wave Processes (head: Prof. Nikolay I. Koroteev)
03/2004 – present: General Physics Institute of Russian Academy of Sciences, Moscow, Russia,
Senior Scientific Researcher (permanent position)
02/2005, 06/2008: Centre Lasers Intenses et Applications (CELIA), Bordeaux, France,
Invited Professor
03/2004 – 06/2004, 08/2005 – 10/2005, 06/2006 – 07/2006 : Max Planck Institute for the Physics of Complex Systems, Dresden, Germany,
Guest Scientific Researcher
11/2002 – 11/2003: Centre Lasers Intenses et Applications (CELIA), France,
Post-doctoral Position, with Dr. E. Constant
9/2000 – 11/2002: International Laser Center, Moscow State University, Russia,
Scientific Researcher
10/1999 – 12/1999: University of Palermo, Italy,
Short-Term Research Visitor, with Prof. G. Ferrante
9/1997 – 7/2000: Physics Department of Moscow State University, International Laser Center, Russia,
Ph.D. Student, with Prof. Viktor T. Platonenko
41 papers in scientific journals and more than 60 conference presentations
Several publications are:
1. Role of Autoionizing State in Resonant High-Order Harmonic Generation and Attosecond Pulse Production, V. Strelkov, Phys. Rev. Lett. 104, 123901 (2010).
2. Shaping of Attosecond Pulses by Phase-Stabilized Polarization Gating", G. Sansone, E. Benedetti, J.P. Caumes, S. Stagira, C. Vozzi, M. Nisoli, L. Poletto, P. Villoresi, V. Strelkov, I. Sola, L. B. Elouga, A. Zair, E. Mevel, E. Constant, Phys. Rev. A 80, 063837 (2009).
3. Generation of isolated attosecond pulses by spatialshaping of a femtosecond laser beam, V V Strelkov, E Mével and E Constant, New Journal of Physics, 10, 083040 (2008).
4. Theory of high-order harmonic generation and attosecond pulse emission by a low-frequency elliptically polarized laser field, V. V. Strelkov, Phys. Rev. A 74, 013405 (2006).
5. High-harmonic generation in a dense medium, V. V. Strelkov, V. T. Platonenko, and A. Becker, Phys. Rev. A 71, 053808 (2005).
6. Controlling attosecond electron dynamics by phase-stabilized polarization gating, I. J. Sola, E. Mevel, L. Elouga, E. Constant, V. Strelkov, L. Poletto, P. Villoresi, E. Benedetti, J.-P. Caumes, S. Stagira, C. Vozzi, G. Sansone and M. Nisoli, Nature Physics 2, 281 (2006).
7. Temporal and spectral studies of high-order harmonics generated by polarization-modulated
infrared fields, I. J. Sola, A. Za？r, R. López-Martens, P. Johnsson, K. Varjú, E. Cormier, J. Mauritsson, A. L’Huillier, V. Strelkov, E. Mével and E. Constant, Phys. Rev. A 74, 013810 (2006).
8. A new similarity measure for histogram comparison and its application in time series analysis, V V Strelkov, Pattern Recognition Letters, 29, 1768 (2008).
9. Review: Generation of a high-order harmonics in a high-intensity laser radiation field; V.T.Platonenko, V.V.Strelkov, Quantum Electronics, 28 (7), 564-583 (1998).
* * Award of Competition of Scientific works of A.M.Prokhorov General Physics Institute, 2009
* * "Dynasty" Foundation personal fellowship, 2006-2008
* * Russian Science Support Foundation personal fellowship, 2006-2007
* * Fellowships of the Max-Planck Society, 2004, 2005, 2006
* * Ministry of Youth, Education and Research of France Fellowship, 2002
* * Russian Foundation for Basic Research Fellowship for Young Scientists, 1999, 2000, 2001
* * George Soros Graduate Student Award from the International Science Foundation, 1997, 1998, 1999
* * Centre for Science and Education of Russian Academy of Sciences Fellowship, 1998
* * Outstanding Young Scientist Award of the Government of Russian Federation, 1997
* * First Award of Competition of Diploma Works of students of the Physics Department of the Moscow State University, 1997
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2010年10月8日