Numerical simulation of the diffraction of optical vortices by a plasmonic lens with a ring structure

In this research, a plasmonic lens with a concentric relief in thin metal film was numerically studied by the (FD)2TD method. Parameters of the plasmonic lens were optimized. It is shown that the silver plasmonic lens operates better than gold one and focuses laser light with wavelength of 633 nm into a spot with full width at half maximum of 0.38λ and maximum intensity of 4.04 a.u. It is shown that silver plasmonic lens could focus cylindrical vector beams, forming several peaks on the circle.