Computer simulations of light focusing with a Fresnel mesowavelength zone plate

The paper presents the results of the numerical simulations of binary phase Fresnel zone plates (FZP) of the mesowavelength sizes and large aperture angles (NA similar to 1) to reveal the main regularities of the formation of the spatial optical near-field structure, as well as to optimize FZP design for obtaining the most intense focus. We show the dimensional parameters of FZP focal region are sensitive both to the depth of phase zones etching and to the type of structural design of the plate. An increase in the number of Fresnel zones leads to the formation of external local focus with a greater intensity.