极紫外阿秒脉冲的色散控制及束线设计  

Dispersion Control and Beamline Design of Extreme Ultraviolet Attosecond Pulses

作　　者：许思源 李远锋 朱孝先 高亦谈 赵昆 朱江峰 张大成 贺新奎[2,3,4] 滕浩 魏志义[2,3,4] Xu Siyuan;Li Yuanfeng;Zhu Xiaoxian;Gao Yitan;Zhao Kun;Zhu Jiangfeng;Zhang Dacheng;He Xinkui;Teng Hao;Wei Zhiyi(School of Physics and Optoelectronic Engineering,Xidian University,Xi'an,Shaanxi 710071,China;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China;Songshan Lake Material Laboratory,Dongguan,Guangdong 523808,China)

机构地区：[1]西安电子科技大学物理与光电工程学院,陕西西安710071 [2]中国科学院物理研究所,北京凝聚态物理国家研究中心,北京100190 [3]中国科学院大学,北京100049 [4]松山湖材料实验室,广东东莞523808

出　　处：《中国激光》2021年第5期147-158,共12页Chinese Journal of Lasers

基　　金：国家重点研发计划(2017YFB0405202,2018YFB1107200);国家自然科学基金(61690221,91850209,11774277);中国科学院仪器研制项目(YZ201658);前沿科学重点研究计划(QYZDJ-SSW-JSC006)。

摘　　要：基于极紫外波段高次谐波产生(high-order harmonic generation,HHG)的光学选通技术已成为目前人们获得孤立阿秒脉冲(isolated attosecond pulse,IAP)的重要手段。由于IAP继承了驱动激光脉冲的光学属性和重复频率,因此具有良好的时空相干性和方向性。近转换极限极短脉宽IAP的产生不仅需要在极紫外区域有较宽的连续光谱支持,还需要对其所携带的本征色散进行补偿。据此,本文从理论上模拟计算了多组阿秒脉冲光谱、本征色散和金属膜材料色散的参数组合,在中心光谱98,120,170 eV附近的结果表明,选用不同厚度的锆膜、钼膜和锡膜对应中心能量的高次谐波可以实现色散补偿。最终确定120 eV中心光子能量加钼膜的组合有可能在较高的产生效率下产生近40 as的IAP。基于上述参数选择,设计了一套由非共线阿秒条纹相机和平场光谱仪组成的极紫外阿秒束线及相应的真空系统,该系统可用于高次谐波及阿秒脉冲的测量。Objective The motion and correlation of electrons are the most fundamental physical processes in all systems based on electromagnetic interaction,and their characteristic time is of the order of attoseconds(i.e.,10^(-18)s).To investigate or control the ultrafast dynamics of electrons,it is necessary to use a tool with the same or even shorter time scale as a reference.The emergence of ultrashort laser pulses provides an ideal means for studying ultrafast phenomena.The changing light field is the fastest physical quantity which can be measured and controlled.Currently,femtosecond pulses shorter than 5 fs or even close to a single optical cycle(the oscillation cycle of an optical field with a wavelength of 800 nm is 2.67 fs)have been obtained,covering the spectrum from infrared to ultraviolet.To obtain attosecond pulses equivalent to the characteristic time of electron motion,the carrier wave spectrum must be shifted to the extreme ultraviolet(XUV)or even soft X-ray whose oscillation cycle is of the order of attoseconds.It requires the interaction of femtosecond laser pulses and gas atoms at a peak intensity that is close to 10^(13)W/cm^(2)or higher to generate high-order harmonics and attosecond pulses in the XUV band.Optical gating techniques based on high-order harmonic generation(HHG)in the XUV band have become crucial to obtain isolated attosecond pulses(IAP).An ultrashort IAP requires an ultrabroad continuous spectrum and its intrinsic chirp(atto-chirp)must be compensated.Methods In the HHG process,after being ionized,the electrons obtain kinetic energy within half a cycle of the driving laser,and they then return and recombine with the ions to radiate XUV photons.The electrons ionized at different times gain different kinetic energies in the electric field,and they return and recombine at different times,causing the XUV photons radiated to have different energies and wavelengths.This process leads to a relative delay between photons with different energies.Thus,the XUV pulses produced via HHG are chirped,wit

关 键 词：激光光学 高次谐波 孤立阿秒脉冲 阿秒脉冲本征色散 阿秒条纹相机 

分 类 号：O434.11[机械工程—光学工程]