任意夹角的双色偏振激光作用下孤立阿秒脉冲的产生

本文选取脉宽为12 fs波长为2000 nm和800 nm的两束线性偏振激光, 适当调节两束激光的偏振方向的夹角θ, 发现当θ=π/2时, 高次谐波谱的第二级平台出现了“漏斗形”凹槽.当θ为π/6时, 得到了290 eV的超宽连续谱的高次谐波发射, 利用小波变换合理的解释了高次谐波形状及截止位置. 在该段连续谱上任意截取70 eV宽度的频率, 都可以得到脉宽约为60 as的孤立阿秒脉冲. 适当减小截取范围可以得到线性偏振的脉宽94 as的孤立阿秒脉冲. 这为实验中产生能灵活调节的孤立阿秒脉冲提供了一种方案.

Generating isolated attosecond pulses at an arbitrary angle of the two-color polarized laser pulse

By adjusting the polarized angle of a two-color laser field that is synthesized by a 12 fs/2000 nm and 12 fs/800 nm,we find that the spectrum of the high-order harmonic generation has a "funnel structure" in the second plateau whenθisπ/2.And whenθisπ/6,a bandwidth of supercontinuum about 290 eV is observed.We illustrate the structure of the high-order harmonic generated spectrum by the time-frequency analysis.An isolated attosecond pulse is obtained by intercepting an arbitrary 70 eV width in the supercontinuum plateau,and whose full width at half maximum(FWHM) is about 60 as.When we intercept a narrow width of the bandwidth of supercontinuum,a linear polarized attosecond pulse with FWHM 94 as is obtained.All those are convenient to generate and use attosecond pulse in experiment.