Transient absorption and reshaping of ultrafast XUV light by laser-dressed helium

Journal Article · Sat Jan 15 04:00:00 EST 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.83.013419· OSTI ID:21537014

Gaarde, Mette B; Schafer, Kenneth J ^[1]; Buth, Christian ^[1]; Tate, Jennifer L ^[1]

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1. Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

We present a theoretical study of transient absorption and reshaping of extreme ultraviolet (XUV) pulses by helium atoms dressed with a moderately strong infrared (IR) laser field. We formulate the atomic response using both the frequency-dependent absorption cross section and a time-frequency approach based on the time-dependent dipole induced by the light fields. The latter approach can be used in cases when an ultrafast dressing pulse induces transient effects, and/or when the atom exchanges energy with multiple frequency components of the XUV field. We first characterize the dressed atom response by calculating the frequency-dependent absorption cross section for XUV energies between 20 and 24 eV for several dressing wavelengths between 400 and 2000 nm and intensities up to 10{sup 12} W/cm{sup 2}. We find that for dressing wavelengths near 1600 nm, there is an Autler-Townes splitting of the 1s{yields}2p transition that can potentially lead to transparency for absorption of XUV light tuned to this transition. We study the effect of this XUV transparency in a macroscopic helium gas by incorporating the time-frequency approach into a solution of the coupled Maxwell-Schroedinger equations. We find rich temporal reshaping dynamics when a 61-fs XUV pulse resonant with the 1s{yields}2p transition propagates through a helium gas dressed by an 11-fs, 1600-nm laser pulse.

• OSTI ID: 21537014
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 1 Vol. 83; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION
CROSS SECTIONS
DIFFERENTIAL EQUATIONS
DIPOLES
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY RANGE
EQUATIONS
EV RANGE
EXTREME ULTRAVIOLET RADIATION
FLUIDS
FREQUENCY DEPENDENCE
GASES
HELIUM
INFRARED RADIATION
LASER RADIATION
MATHEMATICAL SOLUTIONS
MULTIPOLES
NONMETALS
PARTIAL DIFFERENTIAL EQUATIONS
RADIATIONS
RARE GASES
SCHROEDINGER EQUATION
SORPTION
TIME DEPENDENCE
ULTRAVIOLET RADIATION
VISIBLE RADIATION
WAVE EQUATIONS
WAVELENGTHS