Analysis of sub-wavelength focusing generated by radially polarized doughnut Gaussian beam

摘要

A radially polarized doughnut Gaussian beam is first introduced to generate a subwavelength focal spot. The focusing characteristics of a radially polarized doughnut Gaussian beam by a lens with high numerical aperture are investigated based on the Richards-Wolf diffraction integral formulae. Numerical results indicate that a sub-wavelength focusing can be obtained for a radially polarized doughnut Gaussian incident beam. Therefore, the radially polarized doughnut Gaussian beam is of great importance in the super-resolution focusing area.