Analysis of flat beam diffraction by divergent fracxicon in nonparaxial mode

Theoretical and numerical analysis of flat beam diffraction by divergent fracxicon are performed within the nonparaxial scalar model. Using integration by parts of the Rayleigh-Sommerfeld integral of first type and applying the modified method of stationary phase we obtain the expression of the axial complex distribution satisfying the boundary conditions for on the optical axis. The results ob-tained by numerical integration show good agreement with analytical estimates. Numerical examples show that the divergent fracxicon allows to form an extended axial light line with diameter of the or-der of the wavelength longer and more uniform than provides a linear axicon.