The investigation of Gaussian beams and optical vortices diffraction in the near zone of subwavelength optical elements with variable height

Dmitry A. Savelyev

Samara National Research University, Samara, Russian Federation

Abstract: The finite difference time domain method was used to simulate the propagation of Gaussian beams and optical vortices with circular, radial, azimuthal polarization on subwavelength ring gratings with standard and GRIN substrates in this paper. The height of individual zones of the optical elements relief was varied. It was shown that it is possible to select the beam type and element parameters in such a way that a long light needle (up to $8.2\lambda$) and a narrow focal spot are formed on the optical axis (up to $0.33\lambda$).

Keywords: Gaussian beams, optical vortices, FDTD, GRIN, subwavelength ring gratings, Meep.

UDC: 535.42

Received: 27.10.2024
Received in revised form: 12.12.2024
Accepted: 14.02.2025

Language: English