The diffraction of the laser radiation on the two-band axial microelement

Numerically shown, that an optical microelement consisting just two annular zones is useful for tight focusing of laser radiation if the radius of the central zone is half wavelength. The numerical calculations executed in approach of a thin element by means of the plane wave expansion method show good accordance with finite-difference time-domain method (in view three-dimensional structure of an element). Characteristics and features of diffraction of Gaussian beam with linearly polarization on a considered element are investigated.