近日，山东理工大学物理与光电工程学院的孙玉萍及其研究小组与武汉工程学院的汪锋等人合作并取得一项新进展。经过不懈努力，他们成功利用电离门控技术控制阿秒脉冲的螺旋度和椭圆度。相关研究成果已于2024年12月19日在国际知名学术期刊《物理评论A》上发表。

该研究团队从理论上研究了利用电离门控技术，从定向的CO分子中控制生成具有特定螺旋度和任意椭圆率的阿秒脉冲。结果表明，在单色线偏振激光场的驱动下，相邻半个光周期内产生的高阶谐波具有相反的螺旋度，导致阿秒脉冲的螺旋度在脉冲之间交替变化。

通过引入一个弱的二倍频场来创建电离门控，可以有效地控制高阶谐波的产生，通过抑制每隔半个光周期的电子电离，从而滤除具有特定螺旋度的阿秒脉冲。这样便获得了具有相同螺旋度的阿秒脉冲，并且可以通过调整激光场的相对相位来选择性地控制所需的螺旋度。

此外，研究人员还展示了通过调整电离门控激光场中的分子取向，可以控制155阿秒脉冲的椭圆率和螺旋度。

附：英文原文

Title: Control of attosecond-pulse helicity and ellipticity by the ionization-gating technique

Author: Hua Yuan¹, Shiju Chen¹, Feng Wang^2,*, Jiahang Song¹, Chunhui Yang², Tianxin Ou², Ru Zhang², and Yuping Sun^1,†

Issue&Volume: 2024-12-19

Abstract: We theoretically study controlling the generation of an attosecond pulse with specific helicity and arbitrary ellipticity from an oriented CO molecule using the ionization-gating technique. The results show that driven by a one-color linearly polarized laser field, the high-order harmonics generated in adjacent half optical cycles possess opposite helicities, resulting in the helicities of the attosecond pulses alternating from pulse to pulse. The introduction of a weak second harmonic field to create the ionization gating can effectively control high-order harmonic generation to filter out attosecond pulses with a given helicity by suppressing the ionization of the electrons every other half optical cycle. Then attosecond pulses with the same helicity are obtained, and the desired helicity can be selectively controlled by adjusting the relative phase of the laser field. Moreover, we show that controlling the ellipticity and helicity of a 155-as pulse is feasible by tuning the molecular orientation in the ionization-gating laser field.

DOI: 10.1103/PhysRevA.110.063116

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.063116