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DOE OSTI · 1829727

Optical shock-enhanced self-photon acceleration

Franke, P.·Ramsey, D.·Simpson, T. T.·Turnbull, D.·Froula, D. H.·Palastro, J. P.
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Abstract

Photon accelerators can spectrally broaden laser pulses with high efficiency in moving electron density gradients driven in a rapidly ionizing plasma. When driven by a conventional laser pulse, the group velocity walk-off experienced by the accelerated photons and deterioration of the gradient from diffraction and plasma-refraction limit the extent of spectral broadening. In this work, we show that a laser pulse with a shaped space-time and transverse intensity profile overcomes these limitations by creating a guiding density pro le at a tunable velocity. Self-photon acceleration in this profile leads to dramatic spectral broadening and intensity steepening, forming an optical shock that further enhances the rate of spectral broadening. In this new regime, multi-octave spectra extending from 400nm to 60nm wavelengths, which support near-transform limited < 400 as pulses, are generated over < 100 μm of interaction length.

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Franke, P., Ramsey, D., Simpson, T. T., Turnbull, D., Froula, D. H., Palastro, J. P.. 2021-10-22. Optical shock-enhanced self-photon acceleration. https://doi.org/10.1103/physreva.104.043520

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