Recent developments in extreme ultraviolet (XUV) and x-ray radiation sources have pushed pulse energies and durations to unprecedented levels that opened up the era of non-linear XUV and x-ray optics. In this quest, laser driven high order harmonic generation sources providing attosecond resolution in the XUV spectral region enabled XUV-pump-XUV-probe experiments, while Free Electron Laser research infrastructures offer unique x-ray brilliances for highly non-linear interactions and since recently, they too entered the sub-fs temporal regime. This topical review discusses the conceptual intricacies of non-linear XUV and x-ray processes, addresses experimental particularities and highlights recent applications of such processes with emphasis to laser driven XUV-attosecond source related research.

中文翻译：

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极端紫外线中的非线性过程

极紫外（XUV）和X射线辐射源的最新发展将脉冲能量和持续时间推到了前所未有的水平，从而开启了非线性XUV和X射线光学器件的时代。在这一探索中，激光驱动的高次谐波产生源在XUV光谱区域提供了亚秒级的分辨率，从而实现了XUV-pump-XUV-probe实验，而Free Electron Laser研究基础设施为高度非线性的相互作用提供了独特的X射线亮度，并且从最近开始，他们也进入了子fs的时态。这篇专题综述讨论了非线性XUV和X射线过程的概念复杂性，讨论了实验的特殊性，并着重介绍了此类过程的最新应用，重点是激光驱动的XUV-Atoth光源相关研究。