近日，信阳师范大学Chunyang Zhai团队研究了氦氖混合气体产生的近圆偏振阿秒脉冲的螺旋度选择。相关论文于2025年4月17日发表在《物理评论A》杂志上。

研究组提出并从理论上证明了一种使用双色反向旋转圆偏振（BCCP）场在混合氦氖气体中产生螺旋度选择的近圆偏振阿秒脉冲的方法。BCCP场驱动的高次谐波在频域中表现出单个阶次的圆极化，但相邻阶次具有相反的螺旋度。通过利用He-Ne混合物，他们只选择谐波的一个螺旋分量，从而在时域中产生高度椭圆偏振的阿秒脉冲。

研究组基于量子轨道理论和强场近似的分析进一步阐明了阿秒脉冲的偏振是由He和Ne发射的高次谐波的干涉机制控制的。BCCP场和原子混合物的这种组合在实验中不需要对准，大大简化了由一个螺旋分量主导的椭圆偏振谐波的产生，从而为一种高效、稳健的方法产生具有大椭圆率的明亮阿秒脉冲铺平了道路。

附：英文原文

Title: Helicity-selected near-circularly polarized attosecond pulses generated from mixed He-Ne gases

Author: Chunyang Zhai, Xiaosong Zhu, Yingbin Li, Qingbin Tang, Benhai Yu, Pengfei Lan, Peixiang Lu

Issue&Volume: 2025/04/17

Abstract: We present and theoretically demonstrate a method for generating helicity-selected near-circularly polarized attosecond pulses in mixed He-Ne gases using bichromatic counter-rotating circularly polarized (BCCP) fields. High-order harmonics driven by BCCP fields exhibit circular polarization for individual orders in the frequency domain, but adjacent orders have opposite helicities. By utilizing the He-Ne mixture, we select only one helical component of the harmonics, resulting in the generation of highly elliptically polarized attosecond pulses in the time domain. Our analyses based on the quantum-orbit theory and the strong-field approximation further clarify that the polarization of attosecond pulses is governed by the interference mechanism of high-order harmonics emitted by He and Ne. This combination of BCCP fields and an atomic mixture which requires no alignment in experiments significantly simplifies the generation of elliptically polarized harmonics dominated by one helical component, thereby paving the way for an efficient and robust method to generate bright attosecond pulses with large ellipticity.

DOI: 10.1103/PhysRevA.111.043519

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.043519