Beyond the single-atom response in absorption lineshapes: Probing a dense, laser-dressed helium gas with attosecond pulse trains

Abstract

We investigate the absorption line shapes of laser-dressed atoms beyond the single-atom response, by using extreme ultraviolet (XUV) attosecond pulse trains to probe an optically thick helium target under the influence of a strong infrared (IR) field. We study the interplay between the IR-induced phase shift of the microscopic time-dependent dipole moment and the resonant-propagation-induced reshaping of the macroscopic XUV pulse. Our experimental and theoretical results show that as the optical depth increases, this interplay leads initially to a broadening of the IR-modified line shape, and subsequently to the appearance of new, narrow features in the absorption line.

5 pages, 5 figures

References in corpus (4)

• Lorentz meets Fano spectral line shapes: A universal phase and its laser control
• Transient absorption and reshaping of ultrafast XUV light by laser-dressed helium
• Photoabsorption of attosecond XUV light pulses by two strongly laser-coupled autoionizing states
• Resonant enhancement of a single attosecond pulse in a gas medium by a time-delayed control field

Cited by in corpus (13)

• Controlled free-induction decay in the extreme ultraviolet
• First-principles nonequilibrium Green's function approach to transient photoabsorption: Application to atoms
• Extreme-ultraviolet refractive optics
• Probing autoionizing states of molecular oxygen with XUV transient absorption: Electronic symmetry dependent lineshapes and laser induced modification
• Control of Fano resonances and slow light using Bose-Einstein condensates in a nanocavity
• Phase-Resolved Two-Dimensional Spectroscopy of Electronic Wavepackets by Laser-Induced XUV Free Induction Decay
• Attosecond Transient Absorption in Dense Gases: Exploring the Interplay between Resonant Pulse Propagation and Laser-Induced Line Shape Control
• Resonant propagation of x-rays from the linear to the nonlinear regime
• Attosecond transient-absorption spectroscopy of polar molecules
• Probing Stark-induced nonlinear phase variation with opto-optical modulation
• Light-induced states in the transient-absorption spectrum of a periodically pumped strong-field-excited system
• Extracting RABBITT-like phase information from time-dependent transient absorption spectra
• Probing coherent electronic superpositions of singly- and doubly-excited states of krypton with attosecond four-wave mixing spectroscopy