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arXiv · 2503.01786

Longitudinal shaping of plasma waveguides using diffractive axicons for laser wakefield acceleration

N. Tripathi·B. Miao·A. Sloss·E. Rockafellow·J. E. Shrock·S. W. Hancock·H. M. Milchberg
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Abstract

New techniques for the optical generation of plasma waveguides -- optical fibres for ultra-intense light pulses -- have become vital to the advancement of multi-GeV laser wakefield acceleration. Here, we demonstrate the fabrication and characterization of a transmissive eight-level logarithmic diffractive axicon (LDA) for the generation of meter-scale plasma waveguides. These LDAs enable the formation of a Bessel-like beam with controllable start and end locations of the focal line and near-constant intensity on axis. We present measurements of the Bessel-like focal profile produced by the LDA, and of the leading end of the plasma column generated by it. One important feature is the formation of a funnel-mouthed plasma channel entrance that can act as waveguide coupler. We also compare the diffraction efficiency of our 8-level LDA to 4-level and binary versions, with measurements comparing well to theory.

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N. Tripathi, B. Miao, A. Sloss, E. Rockafellow, J. E. Shrock, S. W. Hancock, H. M. Milchberg. 2025-03-03. Longitudinal shaping of plasma waveguides using diffractive axicons for laser wakefield acceleration. https://arxiv.org/abs/2503.01786

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