聚焦高斯涡旋光束焦区电场和磁场的偏振奇点

Electric and magnetic polarization singularities of focused Gaussian vortex beams in the focal region

以高斯涡旋光束为例,研究了聚焦场中电场和磁场的偏振奇点变化规律.结果表明,高斯涡旋光束经透镜聚焦后,在焦区存在二维和三维电场和磁场的偏振奇点,其位置一般不重合.适当改变与焦面的距离以及光阑截断参数等出现圆偏振奇点的移动、产生和湮没.不同二维和三维电场和磁场圆偏振奇点湮没所对应的各参数临界值不同.在二维电场中,几何焦面上会有V点的产生.

Taking the Gaussian vortex beam as an example, the variation of electric and magnetic polarization singularities of focused Gaussian vortex beams is studied. It is shown that in the focal region there exist two- and three-dimensional （2D and 3D） electric and magnetic polarization singularities of focused Gaussian vortex beams, which do not coincide in general. By suitably varying the distance from the focal plane and the truncation parameter, the motion, creation, and annihilation of circular polarization singularities will take place. The critical valuse of the parameters at which a pair of circular polarization singularities of 2D and 3D electric and magnetic fields will annihilate, are not the same. In the 2D electric field the V-point may appear at the focal plane.