Design and chromatic aberration analysis of plasmonic lenses using the finite element method

Abstract

We designed plasmonic lenses and analyzed their chromatic aberration using the finite element method (FEM) in frequency domain with perfectly matched layers (PML). Plasmonic lenses permit subwavelength focusing of light in the visible and in the near infrared. The focal distance of these devices depends on the wavelength operation due to the dispersive characteristics of the lens structures and the refractive index of their constituent materials. With a uniform incident wave normal to the lens surface, focusing of light by surface plasmon polariton (SPPs) through a plasmonic lens is obtained in the axial direction. The design of three plasmonic lenses in Silver (Ag), Gold (Au) and Copper (Cu) films at two central operation wavelengths of 650 nm and 810 nm, in both, cylindrical and rectangular geometries were considered and the chromatic aberration of the lenses were analyzed by monitoring the peak position of the electromagnetic (EM) field when the wavelength changes from 625 nm to 675 nm and from 785 nm to 835 nm.