High-order harmonic generation in liquids in bicircularly polarized laser fields

It is a nonlinear and nonperturbative optical phenomenon that high-order harmonic generation (HHG) can be produced by the interaction of intense laser pulses with liquid targets. The theoretical studies on HHG in liquids based on full dimensional simulations meet the difficulty of very low computational efficiency. Here, we develop an efficient numerical method based on the statistical mechanics in two-dimensional space, which reproduces the experimental HHG measurements very well. We also study the HHG in bicircularly polarized 1 omega + 3 omega laser fields with the same field strength. It is found that near-circularly-polarized harmonics with different ellipticities can be generated in the counterrotating driving lasers. The cutoff energy of HHG in counter- and corotating driving lasers demonstrates a similar dependence of laser field strength and wavelength as that in the case of a linearly polarized driving laser field. This work paves the way for controlling the ultrafast electron dynamics in liquids by manipulating the laser fields.

Automated summary

High-order harmonic generation (HHG) can be produced by the interaction of intense laser pulses with liquid targets, which is a nonlinear and nonperturbative optical phenomenon. The computational efficiency of theoretical studies on HHG in liquids based on full dimensional simulations is very low. In this study, an efficient numerical method based on statistical mechanics in two-dimensional space is developed, which accurately reproduces experimental HHG measurements. The findings also reveal that near-circularly-polarized harmonics with different ellipticities can be generated in counterrotating driving lasers, and the cutoff energy of HHG in counter- and corotating driving lasers shows a similar dependence on laser field strength and wavelength as that in the case of a linearly polarized driving laser field. This work paves the way for controlling ultrafast electron dynamics in liquids by manipulating laser fields.