Stuttgart 2012 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 44: Attosecond physics II

A 44.7: Vortrag

Freitag, 16. März 2012, 12:15–12:30, V57.05

Fractional High-order Harmonic Combs and Energy Tuning by Split-spectrum Field Synthesis — •Philipp Raith, Christian Ott, Christopher Anderson, Andreas Kaldun, Kristina Meyer, Martin Laux, Yizhu Zhang, and Thomas Pfeifer — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany

High-order harmonic generation in argon is experimentally controlled by splitting up a single broadband continuous spectrum into two components and applying a relative time delay. We observe a pronounced energy tuning of the individual harmonics and present an intuitive, quantitative model for explanation: the tuning results from a change of the instantaneous laser frequency at the interference-induced intensity maxima of the driving shaped pulse. Furthermore, we measured combs of fractional (noninteger) high-order harmonics generated by the controlled interference of two attosecond pulse trains with adjustable relative intensity. The noninteger harmonic combs can be fully modulated and are obtained when the driving laser field is shaped such that it forms two intensity maxima with controllable relative intensities. Simulations based on the strong field approximation show excellent agreement with the measurements, thus demonstrating the microscopic (single-atom response) nature of the control mechanism. In total, the attosecond-precision broadband split-spectrum field synthesis provides comprehensive control of high-harmonic generation and a versatile basis for coherent control of electron dynamics in atoms and molecules with tailored attosecond pulses in the extreme ultraviolet region.