We demonstrate that an ultrashort high intensity laser pulse can propagate for hundreds of Rayleigh ranges in a prepared neutral hydrogen channel by generating its own plasma waveguide as it propagates; the front of the pulse generates a waveguide that confines the rest of the pulse. A wide range of suitable initial index structures and gas densities will support this “self-waveguiding” process; the necessary feature is that the gas density on axis is a minimum. Here, we demonstrate self-waveguiding of pulses of at least $1.5\times {10}^{17}\mathrm{W}/{\mathrm{cm}}^2$ (normalized vector potential $a_0\sim 0.3$) over 10 cm, or $\sim 100$ Rayleigh ranges, limited only by our laser energy and length of our gas jet. We predict and observe characteristic oscillations corresponding to mode-beating during self-waveguiding. The self-waveguiding pulse leaves in its wake a fully ionized low-density plasma waveguide which can guide another pulse injected immediately following; we demonstrate optical guiding of such a follow-on probe pulse. The method is well suited to laser wakefield acceleration and other applications requiring a long laser-matter interaction length.

• Received 15 August 2020
• Accepted 12 October 2020

DOI:https://doi.org/10.1103/PhysRevResearch.2.043173

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Published by the American Physical Society