Negro M, Devetta M, Faccialá D, Ciriolo A G, Calegari F, Frassetto F, Poletto L, Tosa V, Vozzi C, Stagira S
Opt Express. 2014 Dec 1;22(24):29778-86. doi: 10.1364/OE.22.029778.
High order harmonic generation (HHG) has shown its impact on several applications in Attosecond Science and Atomic and Molecular Physics. Owing to the complexity of the experimental setup for the generation and characterization of harmonics, as well as to the large computational costs of numerical modelling, HHG is generally performed and modelled in collinear geometry. Recently, several experiments have been performed exploiting non-collinear geometry, such as HHG in a grating of excited molecules created by crossing beams. In such studies, harmonics were observed at propagation directions different from those of the driving pulses; moreover the scattered harmonics were angularly dispersed.In this work we report on a new regime of HHG driven by multiple beams, where the harmonics are generated by three synchronized, intense laser pulses organized in a non-planar geometry. Although the configuration we explore is well within the strong-field regime, the scattered harmonics we observe are not angularly dispersed.
高次谐波产生（HHG）已在阿秒科学以及原子与分子物理学的多个应用中展现出其影响力。由于谐波产生与表征的实验装置较为复杂，以及数值建模的计算成本高昂，HHG通常在共线几何构型中进行并建模。近来，已经开展了多项利用非共线几何构型的实验，例如在交叉光束产生的激发分子光栅中进行HHG。在这类研究中，在与驱动脉冲传播方向不同的方向上观测到了谐波；此外，散射谐波存在角色散。在本工作中，我们报道了一种由多束光驱动的HHG新机制，其中谐波由三个以非平面几何构型排列的同步强激光脉冲产生。尽管我们所探索的构型完全处于强场区域内，但我们观测到的散射谐波并无角色散。
