Article

High-order harmonic generation enhanced by XUV light.

Max-Planck-Institut für Kernphysik, Heidelberg, Germany.
Optics Letters (Impact Factor: 3.18). 09/2011; 36(17):3530-2. DOI: 10.1364/OL.36.003530
Source: PubMed

ABSTRACT The combination of high-order harmonic generation (HHG) with resonant XUV excitation of a core electron into the transient valence vacancy that is created in the course of the HHG process is investigated theoretically. In this setup, the first electron performs a HHG three-step process, whereas the second electron Rabi flops between the core and the valence vacancy. The modified HHG spectrum due to recombination with the valence and the core is determined and analyzed for krypton on the 3d→4p resonance in the ion. We assume an 800 nm laser with an intensity of about 10(14) W/cm2 and XUV radiation from the Free Electron Laser in Hamburg (FLASH) with an intensity in the range 10(13)-10(16)W cm2. Our prediction opens perspectives for nonlinear XUV physics, attosecond x rays, and HHG-based spectroscopy involving core orbitals.

1 Follower
 · 
127 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: High-order harmonic generation (HHG) is a nonlinear optical process usually interpreted as a sequence of ionization of an atom or molecule by a strong laser field and the following recombination under emission of an extreme ultraviolet photon. We investigate HHG for combined infrared and extreme ultraviolet fields acting on a system possessing two essential states, with the excited state being either a bound state or a resonance. We report shifts of the HHG peak positions compared to the HHG spectrum from an infrared field only and a peak splitting depending on the presence of Rabi oscillations.
    Journal of Modern Optics 06/2014; 61(10):845-850. DOI:10.1080/09500340.2013.854422 · 1.17 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: X-ray science is undergoing one of its greatest revolutions to date with the construction of intense x-ray free electron lasers (FELs) in Menlo Park, California, USA (LCLS), Hamburg, Germany (European XFEL), and Harima Science Garden City, Japan (SACLA). These are vast, several-hundred-million dollar machines that provide x-ray pulses that are many million times brighter than current sources. Similarly groundbreaking are the emerging attosecond light sources based on intense, pulsed optical lasers; they are relatively inexpensive laboratory-size instruments. These two emerging radiation sources enable radically new research and have unnumbered potential applications in materials science, chemistry, biology, and physics. Our work aims at bringing the capabilities of HHG-based attosecond sources to FELs [1,2]. First, we theoretically combine high-order harmonic generation (HHG) with resonant x-ray excitation of a core electron into the transient valence vacancy that is created in the course of the HHG process: the frst electron performs a HHG three-step process whereas, the second electron Rabi fops between the core and the transient valence vacancy [Fig. 1]. The modifed HHG spectrum due to recombination with the valence and the core is determined and analyzed —for krypton [1] on the 3d → 4p resonance [Fig. 2] and for neon [2] on the 1s → 2p—in the respective cations in the light of an optical laser and an FEL. Second, we examine HHG where tunnel ionization (frst step) is replaced by direct x-ray ionization of core electron of neon. We use the boosted HHG radiation to predict single attosecond pulses in the kiloelectronvolt regime. For both presented schemes, we fnd substantial HHG yield for the recombination of the continuum electron with the core hole. Our prediction ofers novel prospects for nonlinear x-ray physics, attosecond x rays, and time-resolved chemical dynamics [1,2].
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A method is proposed to engineer the continuum fraction of the electron wave packet in high-order harmonic generation (HHG) such that a quasi-monochromatic recollision with the atomic core is rendered possible even for parts of the wave packet that were launched to the continuum at different laser phases. Because of this, the HHG spectrum is shown to be enhanced in a specified controllable spectral window. The electron wave-packet engineering is achieved via driving HHG by the combined fields of weak x rays and a strong shaped pulse of infrared radiation. Our calculations based on the strong field approximation show how the enhanced spectral window can be controlled by the shaping of the driving infrared pulse. The scheme is illustrated via a semiclassical trajectory-based analysis. © 2012 Optical Society of America
    Journal of the Optical Society of America B 01/2013; 30(1):57-. DOI:10.1364/JOSAB.30.000057 · 1.81 Impact Factor

Preview

Download
1 Download
Available from