近日，哈尔滨工业大学孙秀冬团队研究了在联合啁啾场中由Ne原子产生孤立的椭圆偏振亚100-as脉冲。这一研究成果发表在2025年9月16日出版的《物理评论A》杂志上。

研究组提出了一种利用啁啾红外（IR）场与紫外（UV）场相结合的Ne原子环电流状态产生孤立椭圆偏振短阿秒脉冲的方法。结果发现，在啁啾红外场中，环电流态发射的谐波谱的截止位置有所延长，但谐波效率却比无啁啾红外场有所降低。用半经典三步模型和量子时频分析可以很好地理解这种谐波展宽。

通过在啁啾红外场中引入适当啁啾参数的紫外场，可以提高谐波谱的效率和手性。该分析表明，椭圆极化谐波的产生可归因于电离电子的不对称发射方向。通过优化激光参数，利用宽带椭圆偏振超连续谱获得了椭圆率高达0.94的98-as孤立脉冲。这种方法提供了一种有效的方法来产生和控制低于100倍的孤立椭圆偏振脉冲。

附：英文原文

Title: Generation of isolated elliptically polarized sub-100-as pulses from Ne atoms in combined chirped fields

Author: Si-Qi Zhang, Bing Zhang, Bo Yan, Xiang-Qian Jiang, Jing Guo, Xiu-Dong Sun

Issue&Volume: 2025/09/16

Abstract: We present a method to generate an isolated elliptically polarized short attosecond pulse from the ring-current state of the Ne atom in a chirped infrared (IR) field combined with an ultraviolet (UV) field. We find that the cutoff position of the harmonic spectrum emitted from the ring-current state is extended, but the harmonic efficiency is reduced in a chirped IR field compared with a chirp-free IR field. This harmonic broadening can be well understood by the semiclassical three-step model and the quantum time-frequency analysis. By introducing a UV field into the chirped IR field with a proper chirp parameter, both the efficiency and chirality of harmonic spectrum can be improved. Our analysis indicates that the generation of the elliptically polarized harmonics can be attributed to the asymmetric emission of ionized electrons in the direction. By optimizing the laser parameters, an isolated 98-as pulse with an ellipticity up to 0.94 is obtained by the broadband elliptically polarized supercontinuum. Our approach provides an effective way to generate and control the sub-100-as isolated elliptically polarized pulses.

DOI: 10.1103/sjy5-q3nh

Source: https://journals.aps.org/pra/abstract/10.1103/sjy5-q3nh