优化双色近红外激光及其二次谐波场驱动原子产生孤立阿秒脉冲  

Generation of isolated attosecond pulses from atoms driven by optimized two near-infrared pulses and their second harmonic fields

作　　者：杜进旭 王国利[1] 李小勇 周效信[1,3] Du Jin-Xu;Wang Guo-Li;Li Xiao-Yong;Zhou Xiao-Xin(College of Physics and Electronic Engineering,Northwest Normal University,Lanzhou 730070,China;College of Electrical Engineering,Northwest University for Nationalities,Lanzhou 730030,China;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]西北师范大学物理与电子工程学院,兰州730070 [2]西北民族大学电气工程学院,兰州730030 [3]中国科学院物理研究所,北京凝聚态物理国家实验室,北京100190

出　　处：《物理学报》2022年第23期115-124,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11864037,91850209,11964033)资助的课题.

摘　　要：随着激光技术的快速发展,通过多色激光的相干合成实现波形的调控已成为可能,这为实现超短孤立的阿秒脉冲输出创造了条件.本文基于强场近似方法,优化双色近红外激光与二次谐波场的相干叠加脉冲驱动氖原子产生孤立阿秒脉冲.研究结果表明,在双色近红外基础上加入倍频光后,通过优化激光参数,能使单原子高次谐波的发射性质得到很大的改善,在一定能量范围内接近实现无啁啾发射,从而获得较短的孤立阿秒脉冲.在考虑了气体的宏观传播效应后,选择合适的实验条件,能够产生脉冲宽度达40 as的孤立脉冲.最后研究了气体压强对高次谐波性质和阿秒脉冲的影响.该研究可为实验室利用近红外激光脉冲驱动原子获得超短孤立阿秒脉冲提供参考.With the rapid development of laser technology,it is possible to control optical waveforms by coherent superposition of electric fields with multiple color components,which creates conditions for generating the ultra-short isolated attosecond pulses(IAP).Based on the strong-field approximation theory,this work focuses on the IAP generated by the optimized multicolor field synthesized by two fundamental near-infrared lasers and their second harmonic fields.The results show that by applying frequency-doubled pulses to the near-infrared laser fields and optimizing the laser parameters,the emission properties of high order harmonics from single atom can be greatly improved,and the nearly attochirp-free harmonic emission can be realized within a certain energy range.As a result,shorter IAPs are obtained.With the consideration of the macroscopic propagation effect of gas,the IAP with a pulse width up to 40 as is generated under appropriate experimental conditions.Finally,the effects of gas pressure on the properties of the high-order harmonic and attosecond pulses are also investigated.This study provides useful theoretical guidance for generating ultra-short IAPs with near-infrared laser pulses in experiment.

关 键 词：高次谐波 孤立阿秒脉冲 优化激光波形 宏观传播 

分 类 号：O56[理学—原子与分子物理] TN24[理学—物理]