Tight focusing of elliptically polarized vortex beams.

We study the focusing properties of elliptically polarized vortex beams. Based on vectorial Debye theory, some numerical calculations are given to illustrate the intensity and phase distribution properties of tightly focused vortex beams. It is found that the spin angular momentum of the elliptically polarized vortex beam will convert to orbital angular momentum by the focusing. The influence of corresponding parameters on focusing properties is also investigated in great detail. It is shown that elliptical light spots can be obtained in the focal plane. Moreover the elliptical spot may rotate and the spot shape may change with the change of certain parameters. These properties are quite important for application of this kind of elliptically polarized vortex beam.