The investigation of optical phenomena in the strong-field regime requires few-cycle laser pulses at field strengths exceeding gigavolts per meter (GV/m). Surprisingly, such conditions can be reached by tightly focusing pJ-level pulses with nearly octave spanning optical bandwidth onto plasmonic nanostructures, exploiting the field-enhancement effect. In this situation, the Gouy phase of the focused beam can deviate significantly from the monochromatic scenario. Here, we study the effect of the Gouy phase of a pulse exploited to drive coherent strong-field photocurrents within a plasmonic gap nanoantenna. While the influence of the specific Gouy phase profile in the experiment approaches the monochromatic case closely, this scheme may be utilized to identify more intricate phase profiles at sub-diffraction scale. Our results pave the way for Gouy phase engineering at picojoule (pJ) pulse energy levels, enabling the optimization of strong-field optical phenomena.

中文翻译：

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单周期脉冲驱动的等离子体纳米间隙中光电流的古伊相位效应

在强场范围内研究光学现象需要场强超过千兆伏每米 (GV/m) 的少周期激光脉冲。令人惊讶的是，通过利用场增强效应，将具有近倍频程光学带宽的 pJ 级脉冲紧密聚焦到等离子体纳米结构上，可以达到这样的条件。在这种情况下，聚焦光束的古伊相位可能会显着偏离单色场景。在这里，我们研究了用于驱动等离子体间隙纳米天线内相干强场光电流的脉冲古伊相的影响。虽然实验中特定古伊相位分布的影响非常接近单色情况，但该方案可用于识别亚衍射尺度上更复杂的相位分布。我们的结果为皮焦耳 (pJ) 脉冲能量水平的古伊相工程铺平了道路，从而实现了强场光学现象的优化。