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Hannover 2013 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 43: Poster II

Q 43.34: Poster

Wednesday, March 20, 2013, 16:00–18:30, Empore Lichthof

Real time observation of transient electron density in water irradiated with tailored femtosecond laser pulsesCristian 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)

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