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arXiv · 2210.07736

High-harmonic generation in liquids with few-cycle pulses: effect of laser-pulse duration on the cut-off energy

Angana Mondal·Benedikt Waser·Tadas Balciunas·Ofer Neufeld·Zhong Yin·Nicolas Tancogne-Dejean·Angel Rubio·Hans Jakob Wörner
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Abstract

High-harmonic generation (HHG) in liquids is opening new opportunities for attosecond light sources and attosecond time-resolved studies of dynamics in the liquid phase. In gas-phase HHG, few-cycle pulses are routinely used to create isolated attosecond pulses and to extend the cut-off energy. Here, we study the properties of HHG in liquids, including water and several alcohols, by continuously tuning the pulse duration of a mid-infrared driver from the multi- to the sub-two-cycle regime. Similar to the gas phase, we observe the transition from discrete odd-order harmonics to continuous extreme-ultraviolet emission. However, the cut-off energy is shown to be entirely independent of the pulse duration. This observation is confirmed by ab-initio simulations of HHG in large clusters. Our results support the notion that the cut-off energy is a fundamental property of the liquid, independent of the driving-pulse properties. Combined with the recently reported wavelength-independence of the cutoff, these results confirm the direct sensitivity of HHG to the mean-free paths of slow electrons in liquids. Our results additionally imply that few-cycle mid-infrared laser pulses are suitable drivers for generating isolated attosecond pulses from liquids.

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Angana Mondal, Benedikt Waser, Tadas Balciunas, Ofer Neufeld, Zhong Yin, Nicolas Tancogne-Dejean, Angel Rubio, Hans Jakob Wörner. 2022-10-14. High-harmonic generation in liquids with few-cycle pulses: effect of laser-pulse duration on the cut-off energy. https://doi.org/10.1364/oe.496686

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