近日，印度古瓦哈提理工学院的Partha Das&Tarak Nath及其研究团队取得一项新进展。他们揭示了圆柱矢量光束在非简并四能级原子系统中的线性和非线性传播。相关研究成果已于2024年12月26日在国际知名学术期刊《物理评论A》上发表。

该团队研究了原子系统中探针矢量光束（PVB）两个分量的相位诱导磁化率。原子被制备在非简并的四能级构型中。跃迁由一个偏振控制场和PVB的两个正交偏振分量耦合。研究表明，介质的线性磁化率取决于控制场与PVB之间的相位差，这一特性反映了系统中的损失或增益。

此外，相位差还会导致矢量光束（VBs）在传播过程中发生偏振旋转。研究人员进一步研究了在几个瑞利长度范围内，非线性对VB在介质中传播的影响。对于径向、方位角和螺旋VBs，观察到了自聚焦和自散焦现象。

特殊的链状自聚焦和自散焦，导致形成了一系列具有适度增益的较小光斑。因此，控制磁化率和自聚焦的机制，有望在从吸收体到放大器的转换、高分辨率显微镜以及光学势阱系统等领域中找到应用前景。

附：英文原文

Title: Linear and nonlinear propagation of cylindrical vector beams through a nondegenerate four-level atomic system

Author: Partha Das* and Tarak Nath Dey

Issue&Volume: 2024-12-26

Abstract: We investigate the phase-induced susceptibilities for both components of the probe vector beam (PVB) within an atomic system. The atoms are prepared in a nondegenerate four-level configuration. The transitions are coupled by a polarized control field and two orthogonally polarized components of a PVB. We show that the linear susceptibility of the medium depends on the phase shift between the control field and PVB, characterizing loss or gain in the system. Additionally, the phase shift causes polarization rotation in the vector beams (VBs) as they propagate. We further study the effect of nonlinearity on the VB propagation through the medium for a couple of Rayleigh lengths. The self-focusing and defocusing phenomena are observed for radial, azimuthal, and spiral VBs. The special chain-like self-focusing and defocusing leads to the formation of consecutive smaller spot sizes with moderate gain. Therefore, the mechanism of control of susceptibility and self-focusing may hold promise for applications such as transitioning from an absorber to an amplifier, high-resolution microscopy, and optical trap systems.

DOI: https://doi.org/10.1103/PhysRevA.110.063720

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.063720