Influence of vortex transmission phase function on intensity distribution in the focal area of high-aperture focusing system

Abstract

An analysis of the possibility of reducing lateral size and increasing longitudinal size of high-aperture focal system focus using vortex transmission phase function for different types of input polarization including the general vortex one was carried out. We have shown both analytically and numerically that subwavelength localization for separate components of the vector field is possible at any polarization type. This fact can be important when considering the interaction between laser radiation and materials that are selectively sensitive to different components of electromagnetic field. In order to form substantially subwavelength details in total intensity, specific polarization types and additional apodization of pupil function such as masking by a narrow annular slit, are necessary. The optimal selection of the slit radius allows to balance the tradeoff between focus depth and focal spot size.