阿秒瞬态吸收光谱中的延迟零点标定(特邀)  

Delay Zero Calibration in Attosecond Transient Absorption Spectrum(Invited)

作　　者：岳影 董福龙 叶地发[3] 刘杰 YUE Ying;DONG Fulong;YE Difa;LIU Jie(Graduate School,China Academy of Engineering Physics,Beijing 100193,China;College of Physics Science and Technology,Hebei University,Baoding 071002,China;Institute of Applied Physics and Computational Mathematics,Beijing 100088,China)

机构地区：[1]中国工程物理研究院研究生院,北京100193 [2]河北大学物理科学与技术学院,保定071002 [3]北京应用物理与计算数学研究所,北京100088

出　　处：《光子学报》2024年第6期61-69,共9页Acta Photonica Sinica

基　　金：国家自然科学基金(Nos.12174034,U2330401)。

摘　　要：模拟了由氦原子能量最低的三个态(1s^(2),1s2s,1s2p)所构成的三能级系统的阿秒瞬态吸收光谱。该系统采用孤立的阿秒极紫外光脉冲作为探测光,能够捕捉红外泵浦光缀饰下的阿秒时间分辨的电子动力学过程。研究发现阿秒瞬态吸收光谱中存在随两束脉冲之间延迟时间变化的高频振荡信号。小波分析显示,其振荡周期分别为红外激光脉冲周期的二分之一、四分之一和六分之一,并且从高频信号中可以提取出延迟零点的位置。本文研究可为实验中延迟零点的标定提供参考。The strong coupling of laser field with atoms and molecules can lead to the shift or even splitting of their energy levels.Observing the spectral changes through laser pump-probe experiments provides insights into the electron dynamics within atoms and molecules.Since the 1960s,ultrafast and intense laser technologies have continuously evolved.Especially in the early 21st century,scientists achieved the synthesis of ultrashort pulses reaching attosecond durations through high harmonic generation of noble-gas atoms under strong laser irradiation.The emergence of attosecond pulses allows for studying the ultrafast electronic dynamics of atoms and molecules within their natural time scales.Attosecond Transient Absorption Spectroscopy(ATAS)utilizes an isolated attosecond Extreme Ultraviolet(XUV)pulse as the probe light and another Infrared(IR)laser pulse with varying time delays as the pump light to obtain attosecond time-resolved electronic dynamics.In recent years,ATAS has found wide applications in various atomic,molecular,and solid-state systems.Among all these applications,how to accurately calibrate the delay-zero from experimental data is an important yet non-trivial task.Recently,HERRMANN J et al.have introduced a novel method to serve this purpose,taking full advantage of the multiphoton transitions in attosecond transient absorption spectroscopy.In their experiment,they observed quarter laser cycle(4ω)oscillations in the transient absorption spectrum of helium,originating from four-photon coupling between high-order odd harmonics in the Attosecond Pulse Train(APT).By utilizing this highly nonlinear 4ωsignal to extract and calibrate the delay-zero,and comparing it with solutions of the time-dependent Schrödinger equation,the accuracy and effectiveness of this method were confirmed.In our work,we further extend this method to ATAS using isolated attosecond pulses as the probe light.Here,we have observed 2ω_(IR),4ω_(IR),and 6ω_(IR) signals and,more importantly,we have found that the high-frequency signal

关 键 词：阿秒瞬态吸收光谱 孤立阿秒脉冲 泵浦探测 小波分析 延迟零点 

分 类 号：O562.2[理学—原子与分子物理]