Kovalev Alexey A, Kotlyar Victor V, Nalimov Anton G
Image Processing Systems Institute of the RAS-Branch of FSRC "Crystallography & Photonics" of the RAS, 151 Molodogvardeyskaya St., 443001 Samara, Russia.
Technical Cybernetics Department, Samara National Research University, 34 Moskovskoe Shosse, 443086 Samara, Russia.
Micromachines (Basel). 2023 Jul 21;14(7):1470. doi: 10.3390/mi14071470.
Elements of micromachines can be driven by light, including structured light with phase and/or polarization singularities. We investigate here a paraxial vector Gaussian beam with an infinite number of polarization singularities residing evenly on a straight line. The intensity distribution is derived analytically and the polarization singularities are shown to exist only in the initial plane and in the far field. The azimuthal angle of the polarization singularities is shown to increase in the far field by π/2. We obtain the longitudinal component of the spin angular momentum (SAM) density and show that it is independent of the azimuthal angle of the polarization singularities. Upon propagation in free space, an infinite number of C-points is generated, where polarization is circular. We show that the SAM density distribution has a shape of four spots, two with left and two with right elliptic polarization. The distance to the transverse plane with the maximal SAM density decreases with decreasing distance between the polarization singularities in the initial plane. Generating such alternating areas with positive and negative SAM density, despite linear polarization in the initial plane, manifests the optical spin Hall effect. Application areas of the obtained results include designing micromachines with optically driven elements.
微机械元件可以由光驱动，包括具有相位和/或偏振奇点的结构化光。我们在此研究一种傍轴矢量高斯光束，其在一条直线上均匀分布着无限多个偏振奇点。通过解析得出了强度分布，并表明偏振奇点仅存在于初始平面和远场中。结果表明，偏振奇点的方位角在远场中增加π/2。我们得到了自旋角动量（SAM）密度的纵向分量，并表明它与偏振奇点的方位角无关。在自由空间中传播时，会产生无限多个C点，在这些点处偏振是圆偏振的。我们表明，SAM密度分布呈四个光斑的形状，两个具有左旋椭圆偏振，两个具有右旋椭圆偏振。到具有最大SAM密度的横向平面的距离随着初始平面中偏振奇点之间距离的减小而减小。尽管初始平面中是线偏振，但产生这种具有正、负SAM密度的交替区域体现了光学自旋霍尔效应。所得结果的应用领域包括设计具有光驱动元件的微机械。
