Product Code: JLA_24_4_042002

Authors:
Lars Englert
Matthias Wollenhaupt
Cristian Sarpe
Dirk Otto
Thomas Baumert
Institut fuer Physik and CINSaT, Universitaet Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany

Laser control of two basic ionization processes on fused silica, i.e., multiphoton ionization and avalanche ionization, with temporally asymmetric pulse envelopes is investigated. Control leads to different final electron densities/energies as the direct temporal intensity profile and the time inverted intensity profile address the two ionization processes in a different fashion. This results in observed different thresholds for material modification on the surface as well as in reproducible lateral structures being an order of magnitude below the diffraction limit (down and below 100 nm at a numerical aperture of 0.5). In this contribution, the morphology of the resulting structures is discussed.