Phase singularities of tightly focused high-order axially symmetric polarized beams in the focal region

Abstract

Abstract Phase singularities of tight focused high-order axially symmetric polarized beams are studied theoretically based on vector diffraction theory. The phase distributions of focused fields are analyzed based on the mathematical expressions of focused fields which are derived using Richards & Wolf diffraction theory, and the numerical simulation results are presented further for beams with different polarization orders. We find that the phase singularities of the tightly focused fields are related with several parameters, such as numerical-aperture of objective lens, polarization order of incident beams, pupil filling factor and so on, which means the phase distributions including singularities properties of the focused fields can be modulated by changing these parameters, and provide some unique applications in optical trapping, microscopy and near-field optics.