Creation of super-resolution non-diffraction beam by modulating circularly polarized light with ternary optical element

Abstract

In order to obtain a super-resolution non-di®raction beam, we propose a fast searching method to design a ternary optical element combined with the circularly polarized light. The optimized results show that a beam with a spot size of 0:356 ̧ and depth of focus of 8:28λ can be achieved by focusing with an oil lens of numerical aperture NA = 1:4 and refractive index of oil n = 1:5. The analysis reveals that the spot size of transverse component is 0:273λ, indicating that the super-resolution e®ect mainly comes from the transverse component. The spot size inside the media can theoretically reach down to 0:273λ because the spot size inside the media is mainly determined by the transverse component.