Input impedance of optical metallic nano dipole over 300 nm – 1200 nm wavelength

In this paper, the input impedance of an optical metallic nano dipole is studied in the 300 nm - 1200 nm wavelength range. Three metals are considered (silver, gold, and aluminum), and the length of the dipole is varied. The study is performed using an in-house developed MoM (Method of Moments) electromagnetic solver. This solver was first thoroughly validated against the commercial FDTD (Finite Difference Time Domain) solver most widely used in this research field: Lumerical. A very good agreement between the two solvers was achieved by carefully tuning the excitation models in the two solvers. It is proven that the selection of a metal for a given sub-band should be based on the input impedance and radiation efficiency.