Le Déroff L, Salières P, Carré B
Commissariat à l'Energie Atomique, Direction des Sciences de Matière/Département de Recherche sur l'Etat Condensé, Atomes et Molécules/Service des Photons, Atomes et Molécules, Centre d'Etudes de Saclay, 91191 Gif-sur-Yvette, France.
Opt Lett. 1998 Oct 1;23(19):1544-6. doi: 10.1364/ol.23.001544.
Using a multilayer spherical mirror, we focus the high-order harmonic radiation produced near 55 nm by the nonlinear interaction of an intense femtosecond laser pulse and a xenon gas jet. The focused XUV beam is characterized by a knife-edge technique in the focal region and by far-field imaging. We show that good-quality beams, nearly two times diffraction limited, can be generated, a conclusion that is at variance with recent predictions of harmonic phase-front distortion. Spot sizes close to 10 microm are obtained, resulting in a high XUV intensity. Increasing the gas density and the length of the generating medium results in a large increase in the divergence in and degradation of the beam quality.
我们使用多层球面镜聚焦由强飞秒激光脉冲与氙气喷流的非线性相互作用在55纳米附近产生的高次谐波辐射。聚焦的极紫外光束在焦区通过刀口技术以及远场成像进行表征。我们表明，可以产生接近两倍衍射极限的高质量光束，这一结论与最近关于谐波波前畸变的预测不一致。获得了接近10微米的光斑尺寸，从而产生了高极紫外强度。增加气体密度和产生介质的长度会导致光束发散大幅增加且光束质量下降。
