A weakly focused light beam is studied numerically in the focal plane, to observe the linear polarization separation and circular polarization accumulation in the beam cross section. This is an example of spin-orbit interaction of light, where the extrinsic orbital angular momentum of light encountered due to focusing is converted into spin angular momentum and causes circular polarization generation and linear polarization separation in different parts of the beam cross section. This effect is studied by evaluating the polarization vector and Stokes vector and angle parameters in the beam cross section in detail. Because of the lens’s spherical geometry and origination of geometric phase, the accumulation of the spin component in the beam cross section is observed to be circularly symmetric, while the linear polarization shows splitting into orthogonal polarization components in the beam cross section. The underlying results may have an important role for understanding the spin-orbit interaction in a weakly focused system at a fundamental level and can be useful in many applications of nanophotonics.

在焦平面上对弱聚焦光束进行数值研究，以观察光束横截面中的线偏振分离和圆偏振累积。这是光的自旋轨道相互作用的一个例子，其中由于聚焦而遇到的光的外在轨道角动量被转换为自旋角动量，并导致在光束横截面的不同部分产生圆偏振和线性偏振分离。通过详细评估光束横截面中的偏振矢量和斯托克斯矢量以及角度参数来研究这种效应。由于透镜的球面几何形状和几何相位的起源，观察到光束截面中自旋分量的积累是圆对称的，而线性偏振在光束截面中显示分裂为正交偏振分量。潜在的结果可能对在基础水平上理解弱聚焦系统中的自旋轨道相互作用具有重要作用，并且可用于纳米光子学的许多应用。