Polarisation response of delay dependent absorption modulation in strong field dressed helium atoms probed near threshold

We present the first measurement of the vectorial response of strongly dressed helium atoms probed by an attosecond pulse train (APT) polarised either parallel or perpendicular to the dressing field polarisation. The transient absorption is probed as a function of delay between the APT and the linea...

Full description

Saved in:
Bibliographic Details
Published in:New journal of physics 2016-08, Vol.18 (8), p.83032
Main Authors: Simpson, E R, Sanchez-Gonzalez, A, Austin, D R, Diveki, Z, Hutchinson, S E E, Siegel, T, Ruberti, M, Averbukh, V, Miseikis, L, Strüber, C S, Chipperfield, L, Marangos, J P
Format: Article
Language:English
Subjects:
Absorption
attosecond
Attosecond pulses
Delay
Helium
Helium atoms
high harmonic generation
Ionization
laser dressing
Linear polarization
Modulation
Physics
pump-probe
Qualitative analysis
Schrodinger equation
Time dependence
transient absorption
ultrafast
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We present the first measurement of the vectorial response of strongly dressed helium atoms probed by an attosecond pulse train (APT) polarised either parallel or perpendicular to the dressing field polarisation. The transient absorption is probed as a function of delay between the APT and the linearly polarised 800 nm field of peak intensity 1.3 × 10 14 W cm − 2 . The APT spans the photon energy range 16-42 eV, covering the first ionisation energy of helium (24.59 eV). With parallel polarised dressing and probing fields, we observe modulations with periods of one half and one quarter of the dressing field period. When the polarisation of the dressing field is altered from parallel to perpendicular with respect to the APT polarisation we observe a large suppression in the modulation depth of the above ionisation threshold absorption. In addition to this we present the intensity dependence of the harmonic modulation depth as a function of delay between the dressing and probe fields, with dressing field peak intensities ranging from 2 × 1012 to 2 × 1014 W cm − 2 . We compare our experimental results with a full-dimensional solution of the single-atom time-dependent (TD) Schrödinger equation obtained using the recently developed abinitio TD B-spline ADC method and find good qualitative agreement for the above threshold harmonics.
ISSN:1367-2630
1367-2630
DOI:10.1088/1367-2630/18/8/083032