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arXiv · 2105.04627

High order Brunel harmonics and supercontinuum formed by a weak optical pump in presence of a strong terahertz field

Ihar Babushkin·Ayhan Demircan·Uwe Morgner·Andrey Savel'ev
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Abstract

Brunel harmonics appear in the optical response of an atom in process of laser-induced ionization, when the electron leaves the atom and is accelerated in the strong optical field. In contrast to recollision-based harmonics, the Brunel mechanism does not require the electron returning to the core. Here we show that in the presence of a strong ionizing terahertz (THz) field, even a weak driving field at the optical frequencies allow for generating Brunel harmonics effectively. The strong ionizing THz pump suppresses recollisions, making Brunel dominant in a wide spectral range. High-order Brunel harmonics may form a coherent carrier-envelope-phase insensitive supercontinuum, compressible into an isolated pulse with the duration down to 100 attoseconds.

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Ihar Babushkin, Ayhan Demircan, Uwe Morgner, Andrey Savel'ev. 2021-05-10. High order Brunel harmonics and supercontinuum formed by a weak optical pump in presence of a strong terahertz field. https://doi.org/10.1103/physreva.106.013115

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