Observation of Refractive Index Line Shape in Ultrafast XUV Transient Absorption Spectroscopy  

作　　者：Mingze Sun Zixiang Jiang Yong Fu Yanrong Jiang Hongtao Hu Chunyuan Bai Zhongyao Yue Jiaming Jiang Hongqiang Xie Cheng Jin Ruxin Li P.B.Corkum D.M.Vileneuvere Ppeng Peng 

机构地区：[1]School of Physical Science and Technology,ShanghaiTech University,Shanghai 201210,Shanghai,China [2]Center for Transformative Science,ShanghaiTech University,Shanghai 201210,Shanghai,China [3]Department of Applied Physics,Nanjing University of Science and Technology,Nanjing,Jiangsu 210094,China [4]Photonics Institute,Technische Universität Wien,A-1040 Vienna,Austria [5]School of Science,East China University of Technology,Nanchang,Jiangxi,China [6]State Key Laboratory of High Field Laser Physics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,Shanghai,China [7]Joint Attosecond Science Laboratory,National Research Council and University of Ottawa,100 Sussex Drive,Ottawa,ON K1A 0R6,Canada [8]Department of Physics,University of Ottawa,25 Templeton St.,Ottawa,ON K1N 6N5,Canada

出　　处：《Ultrafast Science》2023年第4期25-34,共10页超快科学（英文）

基　　金：support of the Joint Centre for Extreme Photonics.Funding:This work is supported by the start-up grant of ShanghaiTech University,Double First-Class Initiative Fund of ShanghaiTech University,Shanghai Rising-Star Program(22QA1406200);National Natural Science Foundation of China(12274297,92250303);Shanghai Science and Technology Program(21511105000);NSERC Discovery Grant program(RGPIN-327147-2012);by the U.S.Army Research Office through Award W911NF-14-1-0383;Part of this research used Beamline 03U of the Shanghai Synchrotron Radiation Facility;supported by the ME2 project under contract no.11227902;the National Natural Science Foundation of China.Y.F.and C.J.are supported by the National Natural Science Foundation of China(12274230,91950102,and 11834004);Funding of NJUST(TSXK2022D005);H.X.is supported by the National Natural Science Foundation of China(12074063 and 12264003)。

摘　　要：Ultrafast extreme ultraviolet (XUV) transient absorption spectroscopy measures the time- and frequencydependent light losses after light–matter interactions. In the linear region, the matter response to an XUV light field is usually determined by the complex refractive index ̃n. The absorption signal is directly related to the imaginary part of ̃n, namely, the absorption index. The real part of ̃n refers to the real refractive index, which describes the chromatic dispersion of an optical material. However, the real refractive index information is usually not available in conventional absorption experiments. Here, we investigate the refractive index line shape in ultrafast XUV transient absorption spectroscopy by using a scheme that the XUV pulse traverses the target gas jet off-center. The jet has a density gradient in the direction perpendicular to the gas injection direction, which induces deflection on the XUV radiation. Our experimental and theoretical results show that the shape of the frequency-dependent XUV deflection spectra reproduces the refractive index line profile. A typical dispersive refractive index line shape is measured for a single-peak absorption;an additional shoulder structure appears for a doublet absorption.Moreover, the refractive index line shape is controlled by introducing a later-arrived near-infrared pulse to modify the phase of the XUV free induction decay, resulting in different XUV deflection spectra. The results promote our understanding of matter-induced absorption and deflection in ultrafast XUV spectroscopy.

关 键 词：Attosecond transient absorption spectroscopy line shape refractive index High Harmonic Generation 

分 类 号：O43[机械工程—光学工程]