偶极子涡旋光束的光斑及其传输研究

Research on Dipole Vortex Beam and Its Propagation

在近轴光束传输理论的前提下,推导了偶极子涡旋光束传输一段距离后光电场的解析表达式,同时得到了观测平面上的光强分布。研究表明,偶极子涡旋光束在传输过程中,双核的倾角会逐渐发生改变,拓扑电荷数较大,观测平面上光斑的中心区域越趋近于圆形暗斑,离心参数较大时,观测平面上光斑的中心区域趋近于矩形亮斑。极值理论分析进一步表明,当满足mw20>d2时,观测平面上存在7个光强极值点,否则存在5个光强极值点。这些结论对分析和了解偶极子涡旋光束能提供指导作用。

Based on the propagation theory of paraxial approximation for optical beam, the analytical expression of the optical electric field is derived for the dipole vortex beam during propagation. The intensity distribution on the observation plane is obtained at the same time. It is shown that the obliquity of the dipole cores of the beam will change during propagation. While the topological charge is bigger, the center of spot on the observation plane tends to be a circular macula; while the off-center parameter is bigger, the center of the spot on the observation tends to be a rectangular bright spot. Further analysis on the extremum of the intensity reveals that if mwv2〉d2 , there exists seven extreme points of light intensity on the observation plane; or else there exists five points.