| Abstract: | Based on the vectorial Debye theory, we investigate the tight focusing of elliptically polarized light beams by high numerical-aperture
(NA) phase Fresnel zone plates (FZP). The conversion of the spin angular momentum (SAM) and the orbital angular momentum (OAM)
in the tight focusing of the elliptically polarized beams is investigated in great detail. It is shown that the direction
and magnitude of the OAM can be directly modulated by the input polarization, providing effective evidence that the SAM carried
by an elliptically polarized light beam is converted into OAM in the tight focusing process. The properties of phase retardation
between x and y components of the focused field are also investigated. It is found that focused field of x and y components still keeps its original elliptical polarization state, indicating that the focused field composed of x and y components still carries SAM, whereas the focused field of z component is changed into carrying OAM. The influences of the total zone number and the phase difference of binary phase
FZPs with high NA on the intensity distribution in the focal plane are also investigated. |
