We report on the spatial and spectral variation of high-order harmonics generation from noble gases when driven by high-repetition rate femtosecond laser with different peak intensity and polarization states. Ar, Xe, and Kr were chosen for the generation of coherent extreme ultraviolet radiation. We observe that increasing the intensity of the driving pulses (DPs) leads to disappearance of harmonics yield in the on-axis part of the spatial distribution of the harmonics in Xe target, contrary to Ar and Kr. This observation is attributed to the higher ionization potential of the latter gases. Spectral depletion of harmonics generated in Ar and Xe using radially and azimuthally polarized Gaussian–Laguerre two-color DPs is also observed. The significant depletion in the spectral distribution of harmonics is obtained when two-color pump (TCP) scheme is applied. We demonstrate how TCP scheme with azimuthally polarized DPs can be used as a tool to control the spectral distribution of harmonics generated from gas atoms during strong field by utilizing the presence of second harmonic electromagnetic field.

中文翻译：

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惰性气体中产生的高次谐波的空间和光谱变化

我们报告了当由具有不同峰值强度和偏振态的高重复率飞秒激光驱动时，惰性气体产生的高次谐波的空间和光谱变化。选择 Ar、Xe 和 Kr 来产生相干的极紫外辐射。我们观察到，增加驱动脉冲 (DP) 的强度会导致 Xe 靶中谐波空间分布的轴上部分的谐波产量消失，这与 Ar 和 Kr 相反。该观察结果归因于后者气体的较高电离势。还观察到使用径向和方位角极化的高斯-拉盖尔双色 DPs 在 Ar 和 Xe 中产生的谐波的光谱耗尽。当应用双色泵 (TCP) 方案时，谐波的光谱分布显着减少。我们演示了如何使用具有方位角极化 DP 的 TCP 方案作为一种工具，通过利用二次谐波电磁场的存在来控制强场期间气体原子产生的谐波的光谱分布。