Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Conference on Lasers and Electro-Optics

Attosecond Transient Absorption and Four-Wave Mixing with Tunable IR Pulses

Nathan Harkema, Jens E. Bækhøj, Kenneth J. Schäfer, Mette B. Gaarde, Chen-Ting Liao, Arvinder S. Sandhu

Published Jan 1, 2018• 0 citations
Publisher

Abstract

We extend the technique of attosecond transient absorption spectroscopy by incorporating tunable IR pulses from an OPA. This technique is used to control Autler-Townes splitting and drive XUV four-wave mixing processes in Helium.
DOI
10.1364/cleo_qels.2018.ff1p.2

Related papers

Phase-matched perturbative wave-mixing in XUV region

Khuong Ba Dinh, Khoa Anh Tran, Peter Hannaford +1 more

We demonstrate generation of phase-matched four-wave mixing frequencies in XUV region by using a driving field and two control fields. Our findings are promising to produce an XUV quasi-continuum for attosecond pulses synthesis.

Conference on Lasers and Electro-Optics•Jan 1, 2019•0 citations

Attosecond transient absorption in dense gases: Exploring the interplay between resonant pulse propagation and laser-induced line-shape control

Chen-Ting Liao, Arvinder S. Sandhu, Seth Camp +2 more

We investigate the evolution of extreme ultraviolet (XUV) spectral line shapes in an optically thick helium gas under near-infrared (IR) perturbation. In our experimental and theoretical work, we systematically vary the IR intensity, time-delay, gas density, and IR polarization parameters to study line-shape modifications induced by collective interactions in a regime beyond the single-atom response of a thin, dilute gas. In both experiment and theory, we find that specific features in the frequency-domain absorption profile, and their evolution with propagation distance, can be attributed to the interplay between resonant attosecond pulse propagation and IR-induced phase shifts. Our calculations show that this interplay also manifests itself in the time domain, with the IR pulse influencing the reshaping of the XUV pulse propagating in the resonant medium.

arXiv:1602.01526•Physical Review A•Mar 4, 2016•24 citations

Controlling attosecond transient absorption with tunable, non-commensurate light fields

Nathan Harkema, Jens E. Bækhøj, Chen-Ting Liao +3 more

We demonstrate a transient absorption scheme that uses a fixed-spectrum attosecond pulse train in conjunction with a tunable probe laser to access a wide range of nonlinear light-atom interactions. We exhibit control over the time-dependent Autler-Townes splitting of the 1s4p absorption line in helium, and study its evolution from a resonant doublet to a light-induced sideband with changing probe wavelength. The non-commensurate probe also allows for the background-free study of two-infrared-photon emission processes in a collinear geometry. Using this capability, we observe two different emission pathways with non-trivial delay dependencies, one prompt and the other delayed. We identify the nonlinear processes underlying these emissions by comparing the experimental results to calculations based on the time-dependent Schrödinger equation.

Optics Letters•Jul 9, 2018•11 citations

Phase-matched perturbative wave-mixing in XUV region

Khuong Ba Dinh, Khoa Anh Tran, Peter Hannaford +1 more

We demonstrate generation of phase-matched four-wave mixing frequencies in XUV region by using a driving field and two control fields. Our findings are promising to produce an XUV quasi-continuum for attosecond pulses synthesis. © 2019 The Author(s)

Conference on Lasers and Electro-Optics•May 5, 2019•0 citations

Enhancing Autler-Townes splittings by ultrafast XUV pulses

Wei‐Chao Jiang, Hao Liang, Shun Wang +2 more

We study the photoelectron spectra of hydrogen and helium ionized by intense ultrafast two-color XUV laser pulses by numerically solving the time-dependent Schrödinger equation.The photon energy of the pump pulse is tuned to the 1s-2p excitation energy, inducing Rabi oscillations between these bound states and forming an Autler-Townes (AT) doublet of dressed states.When ionized by a time-delayed ultrafast XUV pulse with duration shorter than the Rabi oscillation period, we find novel and drastically enhanced AT splittings in the photoionization spectrum.We identify their origin in terms of the temporal interference of two attosecond wave packets whose spectral distribution is controlled by the interplay between Rabi frequency and bandwidth of the probe pulse.These time-dependent features in the spectra can be much larger than the standard AT spacing induced by the pump pulse alone and can be controlled by the time delay and the duration of the probe pulse.

Physical Review Research•Aug 25, 2021•31 citations

Time-domain perspective on Autler-Townes splitting in attosecond transient absorption of laser-dressed helium atoms

Mengxi Wu, Shaohao Chen, Mette B. Gaarde +1 more

We present a theoretical study of the delay-dependent Autler-Townes (AT) splitting in transient absorption spectroscopy of an isolated attosecond pulse in helium atoms subject to a delayed infrared (IR) pulse. We concentrate on cases in which the IR pulse is resonant with the helium $1s2p\text{\ensuremath{-}}1s2s$ transition and provide a time-domain perspective of the dynamics in the delay-dependent pump-probe system. We identify several interesting delay-dependent features in the transient absorption spectrum such as AT splitting, oscillation between absorption and emission at the resonant absorption frequency, and sub-IR-cycles oscillations. We then explain the origins of these features in the time domain in terms of a strongly driven two-level system, in the language of population transfer and coherent control.

Physical Review A•Oct 15, 2013•55 citations
We investigate the evolution of extreme ultraviolet (XUV) spectral line shapes in an optically thick helium gas under near-infrared (IR) perturbation. In our experimental and theoretical work, we systematically vary the IR intensity, time-delay, gas density, and IR polarization parameters to study line-shape modifications induced by collective interactions in a regime beyond the single-atom response of a thin, dilute gas. In both experiment and theory, we find that specific features in the frequency-domain absorption profile, and their evolution with propagation distance, can be attributed to the interplay between resonant attosecond pulse propagation and IR-induced phase shifts. Our calculations show that this interplay also manifests itself in the time domain, with the IR pulse influencing the reshaping of the XUV pulse propagating in the resonant medium.
We demonstrate a transient absorption scheme that uses a fixed-spectrum attosecond pulse train in conjunction with a tunable probe laser to access a wide range of nonlinear light-atom interactions. We exhibit control over the time-dependent Autler-Townes splitting of the 1s4p absorption line in helium, and study its evolution from a resonant doublet to a light-induced sideband with changing probe wavelength. The non-commensurate probe also allows for the background-free study of two-infrared-photon emission processes in a collinear geometry. Using this capability, we observe two different emission pathways with non-trivial delay dependencies, one prompt and the other delayed. We identify the nonlinear processes underlying these emissions by comparing the experimental results to calculations based on the time-dependent Schrödinger equation.
We study the photoelectron spectra of hydrogen and helium ionized by intense ultrafast two-color XUV laser pulses by numerically solving the time-dependent Schrödinger equation.The photon energy of the pump pulse is tuned to the 1s-2p excitation energy, inducing Rabi oscillations between these bound states and forming an Autler-Townes (AT) doublet of dressed states.When ionized by a time-delayed ultrafast XUV pulse with duration shorter than the Rabi oscillation period, we find novel and drastically enhanced AT splittings in the photoionization spectrum.We identify their origin in terms of the temporal interference of two attosecond wave packets whose spectral distribution is controlled by the interplay between Rabi frequency and bandwidth of the probe pulse.These time-dependent features in the spectra can be much larger than the standard AT spacing induced by the pump pulse alone and can be controlled by the time delay and the duration of the probe pulse.
We present a theoretical study of the delay-dependent Autler-Townes (AT) splitting in transient absorption spectroscopy of an isolated attosecond pulse in helium atoms subject to a delayed infrared (IR) pulse. We concentrate on cases in which the IR pulse is resonant with the helium $1s2p\text{\ensuremath{-}}1s2s$ transition and provide a time-domain perspective of the dynamics in the delay-dependent pump-probe system. We identify several interesting delay-dependent features in the transient absorption spectrum such as AT splitting, oscillation between absorption and emission at the resonant absorption frequency, and sub-IR-cycles oscillations. We then explain the origins of these features in the time domain in terms of a strongly driven two-level system, in the language of population transfer and coherent control.