Quintard L, Strelkov V, Vabek J, Hort O, Dubrouil A, Descamps D, Burgy F, Péjot C, Mével E, Catoire F, Constant E
Université de Bordeaux, CNRS, CEA, Centre Laser Intenses et Applications (CELIA), 43 rue P. Noailles, 33400 Talence, France.
Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilova Street, Moscow 119991, Russia.
Sci Adv. 2019 Apr 5;5(4):eaau7175. doi: 10.1126/sciadv.aau7175. eCollection 2019 Apr.
By experimentally studying high-order harmonic beams generated in gases, we show how the spatial characteristics of these ultrashort extreme-ultraviolet (XUV) beams can be finely controlled when a single fundamental beam generates harmonics in a thin gas medium. We demonstrate that these XUV beams can be emitted as converging beams and thereby get focused after generation. We study this optics-less focusing using a spatially chirped beam that acts as a probe located inside the harmonic generation medium. We analyze the XUV beam evolution with an analytical model and obtain very good agreement with experimental measurements. The XUV foci sizes and positions vary strongly with the harmonic order, and the XUV waist can be located at arbitrarily large distances from the generating medium. We discuss how intense XUV fields can be obtained with optics-less focusing and how the order-dependent XUV beam characteristics are compatible with broadband XUV irradiation and attosecond science.
通过对气体中产生的高阶谐波光束进行实验研究，我们展示了在稀薄气体介质中单个基波光束产生谐波时，如何精细控制这些超短极紫外（XUV）光束的空间特性。我们证明这些XUV光束可以作为会聚光束发射，从而在产生后聚焦。我们使用位于谐波产生介质内部作为探针的空间啁啾光束研究这种无光学聚焦。我们用解析模型分析了XUV光束的演化，并与实验测量结果取得了很好的一致性。XUV焦点的尺寸和位置随谐波阶数变化很大，并且XUV束腰可以位于离产生介质任意远的距离处。我们讨论了如何通过无光学聚焦获得强XUV场，以及与阶数相关的XUV光束特性如何与宽带XUV辐照和阿秒科学兼容。
