Comparison of simulation diffraction linearly polarized Gaussian beam by a binary axicon with a high numerical aperture integral and difference method

A comparison of two algorithms for modeling the diffraction of an electromagnetic field on the axicon with a high numerical aperture in linear polarization of the illuminating beam. We compare the integral method based on the plane waves expansion and the method of finite difference in time domain - FDTD. The integral method, has shown the suitability for the detection of the major trends, which are then investigated more accurate by method FDTD. When using the computer package Meep for the calculation of FDTD has been investigated dynamic changes of the central spot size at high numerical aperture diffractive axicon.