Schapper F, Holler M, Auguste T, Zaïr A, Weger M, Salières P, Gallmann L, Keller U
Physics Department, ETH Zurich, 8093 Zurich, Switzerland.
Opt Express. 2010 Feb 1;18(3):2987-94. doi: 10.1364/OE.18.002987.
We have spatially and spectrally resolved the high order harmonic emission from an argon gas target. Under proper phase matching conditions we were able to observe for the first time the spatial fine structure originating from the interference of the two shortest quantum paths in the harmonic beam. The structure can be explained by the intensity-dependent harmonic phase of the contributions from the two paths. The spatially and spectrally resolved measurements are consistent with previous spatially integrated results. Our measurement method represents a new tool to clearly distinguish between different interference effects and to potentially observe higher order trajectories in the future with improved detection sensitivity. Here, we demonstrate additional experimental evidence that the observed interference pattern is only due to quantum-path interferences and cannot be explained by a phase modulation effect. Our experimental results are fully supported by simulations using the strong field approximation and including propagation.
我们已在空间和光谱上解析了来自氩气靶的高次谐波发射。在适当的相位匹配条件下，我们首次能够观察到源于谐波束中两条最短量子路径干涉的空间精细结构。该结构可以用两条路径贡献的强度依赖谐波相位来解释。空间和光谱分辨测量结果与先前的空间积分结果一致。我们的测量方法是一种新工具，可清晰区分不同的干涉效应，并有可能在未来通过提高检测灵敏度来观察更高阶轨迹。在此，我们展示了额外的实验证据，表明观察到的干涉图案仅源于量子路径干涉，无法用相位调制效应来解释。我们的实验结果得到了使用强场近似并包括传播的模拟的充分支持。
