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arXiv · 1311.1351

Combined action of the bound-electron nonlinearity and the tunnel-ionization current in low-order harmonic generation in noble gases

U Sapaev·A Husakou·J Herrmann
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Abstract

We study numerically low-order harmonic generation in noble gases pumped by intense femtosecond laser pulses in the tunneling ionization regime. We analyze the influence of the phase-mismatching on this process, caused by the generated plasma, and study in dependence on the pump intensity the origin of harmonic generation arising either from the bound-electron nonlinearity or the tunnel-ionization current. It is shown that in argon the optimum pump intensity of about 100 TW/cm$^2$ leads to the maximum efficiency, where the main contribution to low-order harmonics originates from the bound-electron third and fifth order susceptibilities, while for intensities higher than 300 TW/cm$^2$ the tunnel-ionization current plays the dominant role. Besides, we predict that VUV pulses at 133 nm can be generated with relatively high efficiency of about $1.5\times10^{-3}$ by 400 nm pump pulses.

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U Sapaev, A Husakou, J Herrmann. 2013-11-06. Combined action of the bound-electron nonlinearity and the tunnel-ionization current in low-order harmonic generation in noble gases. https://doi.org/10.1364/oe.21.025582

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