Hannover 2010 – wissenschaftliches Programm
Q 62.4: Vortrag
Freitag, 12. März 2010, 11:15–11:30, F 102
Control of ionization processes by tailored femtosecond pulses in dielectric materials — •Lars Englert, Dirk Otto, Jutta Mildner, Alexander Horn, Matthias Wollenhaupt, and Thomas Baumert — Universität Kassel, Institut für Physik und CINSaT, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany
Femtosecond laser pulses tailored by spectral phase modulation are successfully used for coherent control of atoms and molecules [1,2]. We present experiments  and simulations on the ionization processes in a wide band gap material with tailored femtosecond laser pulses.
On the ultrafast timescale tailored laser pulses are used to excite electrons from the valence band to quasifree states in the conduction band by multiphoton ionization and avalanche ionization. Relaxation back to the valence band or trapping to interbandgap states leads to depopulation of the quasi free states. Reaching a critical quasifree electron density results in material ablation.
The effects of laser pulses with asymmetric intensity and frequency distributions in the time domain are studied with respect to material ablation thresholds and structure morphologies on the nanometer scale.
 M. Wollenhaupt et al., Annu. Rev. Phys. Chem. 56, 25–56 (2005)
 T. Brixner et al., Chap. 9, “Femtosecond Laser Spectroscopy”, Editor P. Hannaford, Springer (2005)
 L. Englert et al., Opt. Express 15, 17855 (2007)