Optical needle formation by subwavelength optical elements using high-performance computer systems

The optical vortex diffraction on subwavelength optical elements with a standard and GRIN substrate using the finite difference time domain method was simulated in this paper. The possibility of increasing the light needle (up to  7.86λ) for input radiation with azimuthal and radial polarization was shown using a GRIN substrate and a subwavelength element with zones alternating in height.