Düsseldorf 2007 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 4: Nichtlineare optische Effekte und Lichtquellen I
Q 4.4: Vortrag
Montag, 19. März 2007, 11:15–11:30, 5J
Linear-circular dichroism in the high-order multiphoton ionization in dielectrics — •Vasily V. Temnov1, Klaus Sokolowski-Tinten2, Ping Zhou2, Abdalla El-Khamhawy2, and Dietrich von der Linde2 — 1Experimentelle Physik IIb, Universität Dortmund, Otto-Hahn-Str. 4, 44221 Dortmund, Germany — 2Institut für Experimentelle Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany
We apply the ultrafast time-resolved imaging interferometry [1] to follow the evolution of free carriers in fused silica and sapphire generated by single intense linearly or circularly polarized femtosecond laser pulses. The density ρ (I) of laser-generated carriers just after laser excitation is investigated as a function of the intensity I and polarization state of the applied pump pulses. For both materials and both pump polarizations we found the scaling law to be ρ (I)∼ I6 at intensities around 10 TW/cm2, a clear evidence of six-photon ionization with the lowest order needed to cross the energy band gap. The rate of 6-photon ionization is found to be significantly higher for the linear polarization of the pump pulses [2], which represents the experimental verification of theoretical predictions for high-order multiphoton ionization already made in the early seventies [3].
[1] V.V. Temnov, K. Sokolowski-Tinten, P.Zhou, D. von der Linde, Appl. Phys. A 78, 483 (2004); J. Opt. Soc. Am B 23, 1954 (2006)
[2] V.V. Temnov, K. Sokolowski-Tinten, P. Zhou, A. El-Khamhawy and D. von der Linde, Phys. Rev. Lett 97, 237403 (2006)
[3] H.R. Reiss, Phys. Rev. Lett. 29, 1129 (1972)