arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0910.0129physics.optics
收藏

强聚焦光束中Angular Momentum变换的简单解析模型

A Simple Analytical Model of the Angular Momentum Transformation in Strongly Focused Light Beams

A. Ya. Bekshaev

摘要:

提出了一种描述强聚焦光学系统中矢量光束变换的光线光学模型。与通常的基于焦平面附近的聚焦场分布的方法不同,我们采用直接在出瞳附近形成的变换光束图案。在该截面中,输出场分布的细节具有较小的物理意义,但是适当地允许入射光束偏振状态的变换。这使得能够获得自旋和轨道角动量表示,这是有效的变换光束空间中的任何地方。对于只受圆孔限制的横向均匀圆偏振入射光束,给出了简单的解析结果。分析了输出光束的自旋和轨道角动量的行为及其与聚焦强度(孔径角)的关系。所得到的解析结果与空间非均匀高斯光束和拉盖尔-高斯光束的计算结果在定性和定量上都有很好的一致性。在拉盖尔-高斯光束的应用中,该模型为分析已经具有自旋和轨道角动量混合的光束的角动量变换提供了可能。该模型为自旋-轨道角动量转换的定性分析提供了有效和物理透明的手段。它可以推广到具有复杂空间结构和偏振结构的入射光束。

英文摘要:

A ray-optics model is proposed to describe the vector beam transformation in a strongly focusing optical system. In contrast to usual approaches basing on the focused field distribution near the focal plane, we employ the transformed beam pattern formed immediately near the exit pupil. In this cross section, details of the output field distribution are of minor physical interest but proper allowance is made for transformation of the incident beam polarization state. This enables to obtain the spin and orbital angular momentum representations which are valid everywhere in the transformed beam space. Simple analytical results are available for the transversely homogeneous circularly polarized incident beam limited only by the circular aperture. Behavior of the spin and orbital angular momenta of the output beam and their dependences on the focusing strength (aperture angle) are analyzed. The obtained analytical results are in good qualitative and reasonable quantitative agreement to the calculation performed for the spatially inhomogeneous Gaussian and Laguerre-Gaussian beams. In application to Laguerre-Gaussian beams, the model provides possibility for analyzing the angular momentum transformation in beams already possessing some mixture of the spin and orbital angular momenta. The model supplies efficient and physically transparent means for qualitative analysis of the spin-to-orbital angular momentum conversion. It can be generalized to incident beams with complicated spatial and polarization structure.

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。

↑