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Extreme-ultraviolet spectral compression by four-wave mixing


Extreme-ultraviolet (XUV) sources including high-harmonic generation (HHG), free-electron lasers (FELs), soft-X-ray lasers and laser-driven plasmas are widely used for applications ranging from femtochemistry and attosecond science to coherent diffractive imaging and EUV (or XUV) lithography. The bandwidth of the XUV light emitted by these sources reflects the XUV generation process used. Whereas light from soft-X-ray lasers1 and seeded XUV FELs2 typically has a relatively narrow bandwidth, plasma sources and HHG sources often emit broadband XUV pulses3. Since these characteristic properties of a given source impose limitations on applications, techniques enabling modification of the bandwidth are highly desirable. Here we introduce a concept for efficient spectral compression by four-wave mixing (FWM), exploiting a phase-matching scheme based on closely-spaced resonances. We demonstrate the compression of broadband radiation in the 145–130 nm wavelength range into a narrow-bandwidth XUV pulse at 100.3 nm wavelength in the presence of a broadband near-infrared (NIR) pulse in a krypton gas jet. Our concept provides new possibilities for tailoring the spectral bandwidth of XUV beams.

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Fig. 1: XUV bandwidth compression scheme in krypton.
Fig. 2: Experimental demonstration of XUV compression by means of FWM.
Fig. 3: Comparison of XUV spectral intensities.
Fig. 4: Simulated propagation-dependent intensity of the narrowband feature.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

The codes that produced the modelled data within this paper and other findings of this study are available from the corresponding author upon reasonable request.


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We would like to thank A. A. Ünal for his support and M. Ivanov, M. Richter, F. Morales, A. Husakou and S. Patchkovskii for helpful discussions.

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Authors and Affiliations



B.S. had the idea for the bandwidth compression scheme. L.D., B.S. and V.S. performed the measurements. M.V. performed the TDSE and Maxwell equation calculations. L.D. performed the perturbative calculations. L.D., B.S. and O.K. performed the data analysis. All authors contributed to the creation of the manuscript.

Corresponding authors

Correspondence to L. Drescher or B. Schütte.

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The authors declare no competing interests.

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Peer review information Nature Photonics thanks the anonymous reviewers for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Photoelectron spectrum of Xe ionized by the narrow bandwidth feature around 12.365 eV.

The kinetic energy spectrum is calculated from Abel-inverted photoelectron momentum distribution by angular integration between 85 and 95. A non-linear least squares fit of a Gaussian profile yields a FWHM of 4.0 +/- 0.3 meV (solid line). For more information see Supplementary Information.

Extended Data Fig. 2 Efficiency estimation.

XUV spectra have been recorded for a minimal NIR intensity (destructive interference, blue line) and maximal NIR intensity (constructive interference, orange line). In the maximal NIR intensity, the narrow-bandwidth emission at 12.365 eV is observed, together with a decreased spectral intensity in the region between 9.0 eV and 9.64 eV. To estimate efficiencies, the emission (orange shade) and the incident area between 9 eV and 9.64 eV (blue shade) areas are calculated. For more information see Supplementary Information.

Supplementary information

Supplementary Information

Supplementary Figs. 1–5, discussion and refs. 1–12.

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Drescher, L., Kornilov, O., Witting, T. et al. Extreme-ultraviolet spectral compression by four-wave mixing. Nat. Photonics 15, 263–266 (2021).

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