Bremen 2017 – wissenschaftliches Programm
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K: Fachverband Kurzzeitphysik
K 1: Meßtechnik - Optische Verfahren und veränderliche Plasmen
K 1.4: Vortrag
Montag, 13. März 2017, 15:15–15:35, GW2 B2890
Characterization of attosecond pulse trains with megahertz repetition rate by interference of two-photon transitions — •Stephan Heinrich1,2, Alexander Guggenmos1,2, Fabian Apfelbeck1, and Ulf Kleineberg1,2 — 1LMU München, Fakultät für Physik, Garching, Germany — 2MPQ, Garching, Germany
The necessary IR intensity for high harmonic generation (HHG) in the XUV spectral range has limited previous experiments to kilohertz repetition rates. In the course of the MEGAS project (megahertz attosecond pulses for ultrafast photoelectron spectroscopy) in cooperation with the two Fraunhofer-Institutes IOF and ILT a novel HHG source with megahertz repetition rate was developed. It consists of an enhancement cavity with several kW circulating power in which attosecond pulse trains (APT) are generated.
Using the RABBITT technique (reconstruction of attosecond beating by interference of two-photon transitions) these pulse trains are then characterized by focusing them into a gas jet and detecting the emitted photoelectrons. Two-photon transitions give rise to sidebands which allow for the reconstruction of the electrical field of the APTs, which has never been done before at comparable repetition rates.
We present first experimental results of HHG at megahertz repetition rate and our progress in the complete characterization of APTs with a 10 kHz system. Once the megahertz HHG source is fully characterized, we are planning to use RABBITT in combination with angular resolved detection for experiments investigating photoemission delays and band structures in solid state targets.