Ultraviolet surprise: Efficient soft x-ray high-harmonic generation in multiply ionized plasmas.

Science 2015 Dec 3;350(6265):1225-31. Epub 2015 Dec 3.

JILA, University of Colorado, Boulder, CO 80309, USA.

High-harmonic generation is a universal response of matter to strong femtosecond laser fields, coherently upconverting light to much shorter wavelengths. Optimizing the conversion of laser light into soft x-rays typically demands a trade-off between two competing factors. Because of reduced quantum diffusion of the radiating electron wave function, the emission from each species is highest when a short-wavelength ultraviolet driving laser is used. However, phase matching--the constructive addition of x-ray waves from a large number of atoms--favors longer-wavelength mid-infrared lasers. We identified a regime of high-harmonic generation driven by 40-cycle ultraviolet lasers in waveguides that can generate bright beams in the soft x-ray region of the spectrum, up to photon energies of 280 electron volts. Surprisingly, the high ultraviolet refractive indices of both neutral atoms and ions enabled effective phase matching, even in a multiply ionized plasma. We observed harmonics with very narrow linewidths, while calculations show that the x-rays emerge as nearly time-bandwidth-limited pulse trains of ~100 attoseconds.



Download full-text PDF

Source
http://jila.colorado.edu/popmintchev/PDFs/PopmintchevUVDrive
Web Search
http://www.sciencemag.org/cgi/doi/10.1126/science.aac9755
Publisher Site
http://dx.doi.org/10.1126/science.aac9755DOI Listing
December 2015
345 Reads
3 Citations
31.480 Impact Factor

Publication Analysis

Top Keywords

high-harmonic generation
12
soft x-ray
8
multiply ionized
8
identified regime
4
number atoms--favors
4
atoms--favors longer-wavelength
4
lasers identified
4
regime high-harmonic
4
mid-infrared lasers
4
longer-wavelength mid-infrared
4
generation driven
4
waveguides generate
4
generate bright
4
bright beams
4
lasers waveguides
4
ultraviolet lasers
4
driven 40-cycle
4
40-cycle ultraviolet
4
large number
4
addition x-ray
4

References

(Supplied by CrossRef)

1987

JETP LETT 1987

Krause et al.
Physical Review Letters 1992

Lewenstein et al.
1994

J PHYS AT MOL OPT PHYS 1988

Rundquist et al.
Science 1998

Physical Review Letters 1997

1997

Corkum et al.
Optics letters 1994

Sansone et al.
Science 2006

Siemens et al.
Nature materials 2010

Similar Publications