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Q: Fachverband Quantenoptik und Photonik

Q 43: Poster II

Q 43.34: Poster

Mittwoch, 20. März 2013, 16:00–18:30, Empore Lichthof

Real time observation of transient electron density in water irradiated with tailored femtosecond laser pulses — Cristian Sarpe, Jens Köhler, Thomas Winkler, •Bastian Zielinski, Nadine Götte, Jutta Mildner, Matthias Wollenhaupt, and Thomas Baumert — University of Kassel, Institute of Physics and CINSaT, D–34132 Kassel, Germany

Ionization mechanisms in water irradiated with bandwidth-limited and temporally asymmetric femtosecond laser pulses are investigated via ultrafast spectral interferometry [1]. By using a novel common-path interferometer with an enlarged temporal measurement window we observe directly the dynamics of a free electron plasma generated by shaped pulses. We proved that a temporally asymmetric pulse and its time reversed counterpart address multiphoton and avalanche ionization mechanisms in a different fashion as suggested for solid dielectrics [2,3]. Positive third-order dispersion shaped pulses produce a much higher free electron density than negative ones at the same fluence, instantaneous frequency and focusing conditions. From the experimental data obtained after irradiation with bandwidth-limited and shaped pulses the multiphoton and avalanche coefficients were determined using a generic rate equation [4].

[1] C. Sarpe et al. New. J. Phys. 14, 075021, (2012)

[2] L. Englert et al. Opt. Express 15, 17855, (2007)

[3] L. Englert et al., Appl. Phys. A 92, 749, (2009)

[4] J. Noack and A. Vogel et al., IEEE J. of Quantum Electron. 35, 1156, (1999)