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arXiv 2409.20145physics.optics
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非傍轴焦区中横向自旋动力学的实验测量

Experimental Measurement of Transverse Spin Dynamics in the Nonparaxial Focal Region

Nitish Kumar, Cyriac Raju, Dinesh N. Naik, Nirmal K. Viswanathan

AI总结:

本文通过介质镜轴向扫描结合干涉仪与Stokes参数测量,实验研究了圆偏振高斯光束非傍轴焦区中的相位-偏振奇点及横向自旋动力学,揭示了螺旋度无关和相关的自旋行为。

摘要:

复杂光场在三维空间中的叠加是多种非平凡波动现象的基础。其中重要的是非均匀偏振分布及其拓扑特性,这导致了横向自旋、横向动量及其动力学的出现。本文在圆偏振高斯输入光束的非傍轴焦区中对这些方面进行了实验测量。将一面介质镜置于焦区内,沿轴向扫描,利用干涉仪和空间分辨Stokes参数测量获得回射输出光束中的相位和偏振变化。通过识别光束截面中的相位和偏振奇点及其随镜面位置变化的行为,我们得以绘制并研究非傍轴焦区中的相位-偏振变化。识别并追踪了输出光束中C点奇点周围的lemon-monstar型偏振图样,以研究输入光束右旋和左旋圆偏振下的横向自旋动力学。直接测量非傍轴焦区中横向和纵向自旋动力学的输入光束偏振螺旋度无关和螺旋度相关方面,是本文报告的重要发现。所提出并演示的测量方法使我们能够更详细地研究非傍轴焦区,并有望揭示其他复杂的光场效应。

英文摘要:

The superposition of complex optical fields in three-dimension (3D) is the basis of several non-trivial wave phenomena. Significant among them are the non-uniform polarization distribution and their topological character, leading to the emergence of transverse spin, transverse momentum, and their dynamics. These aspects are experimentally measured in the nonparaxial focal region of a circularly-polarized Gaussian input beam. A dielectric mirror, kept in the focal region, is axially scanned to obtain the phase and polarization variations in the retro-reflected output beam using an interferometer and spatially-resolved Stokes parameter measurements. The identification of phase and polarization singularities in the beam cross-section and their behaviour as a function of the mirror position enabled us to map and study the phase-polarization variations in the nonparaxial focal region. The lemon-monstar type polarization patterns surrounding the C-point singularity in the output beam are identified and tracked to study the transverse spin dynamics for right- and left- circular polarization of the input beam. Direct measurement of the input beam polarization helicity-independent and helicity-dependent aspects of the transverse and longitudinal spin dynamics in the nonparaxial focal region are the significant findings reported here. The proposed and demonstrated measurement method allows us to investigate the nonparaxial focal region in more detail and has the potential to unravel other intricate optical field effects.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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