Impedance Evaluation of Plasmonic Nano Dipole Antennas Based on Guided TE Mode

We investigate the input impedance of a plasmonic nano dipole antenna topology, focusing on guided quasi-transverse electric (TE) modes using the finite difference frequency domain method at a single frequency. These guided modes propagate along an optical transmission line, generated by confined optical fields within the antenna feed gap, ultimately converting into photons by the emitting antenna. Our study considers plasmonic metals such as gold, silver, copper, zinc, and their alloys. We vary the length, height, and feed gap distance of a gold nano dipole prototype, illustrating the antenna impedance. We demonstrate that the selection of metal depends on an optimized input impedance criterion. The simulation employs the finite difference frequency domain method to analyze electric and magnetic fields, displacement current, input impedance profiles, and voltage across the sides of the gold dipole, serving as our reference prototype. Additionally, we evaluate dipoles composed of silver, copper, gold-silver, and copper-zinc alloys for input impedance characteristics.