Abstract

The introduction of novel experimental methods for the generation and control of extreme ultraviolet (XUV) spectra via high order harmonic generation (HHG) has determined the rapid progress in the field of attosecond science. A new experimental technique for the generation of XUV continua has been recently demonstrated that is based on the polarization gating method with few-cycle phase-stabilized driving pulses. Using aluminum filters of different thicknesses, the chirp of the attosecond pulses can be compensated (e.g. with argon and a 300 nm thick aluminum filter nearly single-cycle 130-as pulses were created) [1]. The carrier-envelope phase of the IR laser and the width of the polarization gate can be adjusted to vary the number of attosecond pulses that are created upon subsequent half-cycles of the IR driving field. We have utilized velocity-map imaging (VMI) in combination with this XUV source to record the dynamics of attosecond electron wave packets in the presence of a strong IR-field [2]. Electron wave packets were created upon XUV-ionization of helium. Using an isolated attosecond pulse, the momentum shift of the electron wave packet in the IR-field can be observed with full angular resolution.

© 2007 IEEE