Coherent superposition of laser-driven soft-X-ray harmonics from successive sources

Abstract

High-order harmonic generation from atoms ionized by femtosecond laser pulses has been a promising approach for the development of coherent short-wavelength sources. However, the realization of a powerful harmonic X-ray source has been hampered by a phase velocity mismatch between the driving wave and its harmonics, limiting their coherent build-up to a short propagation length and thereby compromising the efficiency of a single source. Here, we report coherent superposition of laser-driven soft-X-ray (SXR) harmonics, at wavelengths of 2–5 nm, generated in two successive sources by one and the same laser pulse. Observation of constructive and destructive interference suggests the feasibility of quasi-phase-matched SXR harmonic generation by a focused laser beam in a gas medium of modulated density. Our proof-of-concept study opens the prospect of enhancing the photon flux of SXR harmonic sources to levels enabling researchers to tackle a range of applications in physical as well as life sciences.

Cite this article

Seres, J., Yakovlev, V., Seres, E. et al. Coherent superposition of laser-driven soft-X-ray harmonics from successive sources. Nature Phys 3, 878–883 (2007). https://doi.org/10.1038/nphys775

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