Hannover 2016 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 25: Interaction with strong or short laser pulses II
A 25.7: Vortrag
Mittwoch, 2. März 2016, 16:15–16:30, f107
Circularly polarized high harmonics from Ne atoms — •Lukas Medišauskas1,2,3, Jack Wragg4, Hugo van der Hart4, and Misha Ivanov1,2,5 — 1Imperial College London, United Kingdom — 2Max-Born-Institute, Berlin, Germany — 3Max Planck Institute for the Physics of Complex Systems, Dresden, Germany — 4Queens University Belfast, United Kingdom — 5Humboldt University, Berlin, Germany
An elegant solution to generate circularly polarized harmonics relies on combining circularly polarized fundamental with counter-rotating second harmonic. The harmonic spectra generated by such driving field consists of pairs of left- and right- circularly polarized harmonics. Here, we theoretically investigate this process for a model Ne atoms.
We demonstrate that the harmonic spectra is distinctively different when atomic orbitals with non-zero angular momentum, e.g., 2p, and orbitals with zero angular momentum, e.g., 1s, are considered. Namely, the height of left- and right- circularly polarized harmonics is different by an order of magnitude when 2p orbitals are used. The effect is due the the suppression of the contribution from orbitals counter-rotating with the driving field, i.e., 2p-, and involves the interplay of ionization, recombination and continuum electron propagation dynamics.
In the time domain, the generated spectra from Ne corresponds to a train of attosecond pulses with close to circular polarization. Hence, we demonstrate an amplitude gating scheme that allows to isolate a single attosecond radiation burst and thus attain highly elliptical isolated attosecond pulses.