Lin Zhiyang, Chen You, Pu Jixiong, Lai Xuanyang
Opt Express. 2022 Jan 17;30(2):2636-2645. doi: 10.1364/OE.450049.
In this work, we theoretically study the generation of circularly polarized XUV vortices from high harmonic generation driven by bicircular Laguerre-Gaussian (LG) fields with different frequency ratios, by using the strong-field approximation theory. Our simulation shows that the amplitude of the generated vortices from the ω-3ω bicircular LG field is about one order of magnitude larger than that from the ω-2ω field, irrespective of the harmonic order and the orbital angular momentum of the bicircular driving fields. Our analysis shows that the great increase of the vortex amplitude for the ω-3ω field originates from the harmonic enhancement of a single atom. Furthermore, in terms of quantum-orbit theory, the underlying physics of the harmonic enhancement of the single atom for the ω-3ω field is revealed. Our work provides a simple and robust method to increase the amplitude of the circularly polarized XUV vortices.
在这项工作中，我们利用强场近似理论从理论上研究了由具有不同频率比的双圆拉盖尔 - 高斯（LG）场驱动的高次谐波产生圆偏振极紫外（XUV）涡旋的情况。我们的模拟表明，无论双圆驱动场的谐波阶数和轨道角动量如何，由ω - 3ω双圆LG场产生的涡旋幅度比由ω - 2ω场产生的涡旋幅度大约大一个数量级。我们的分析表明，ω - 3ω场的涡旋幅度大幅增加源于单个原子的谐波增强。此外，根据量子轨道理论，揭示了ω - 3ω场中单个原子谐波增强的潜在物理机制。我们的工作提供了一种简单且稳健的方法来增加圆偏振XUV涡旋的幅度。
