Excitation enhancement of surface plasmon polaritons from an annular plasmonic coupler based on internal corrugations and a central nanowire

A novel plasmonic structure composed of an annular configuration based on internal corrugations that are teeth-shaped with a central nanowire is proposed as a plasmonic coupler. This structure is designed to enhance the surface plasmon polaritons (SPPs) simulated using a finite element method implemented in COMSOL Multiphysics. The simulation results show the crucial dependence on the structural parameters, including nanowire radius, teeth profile, and nanoslit width, to enhance the SPP excitation. Furthermore, by systematically varying these parameters and analyzing the behavior of the power flow and the electric field profiles, it has been found that the proposed plasmonic coupler has a distinct advantage in enhancing the coupling of more energy from incident light at the central nanowire, thus allowing the structure to confine and focus a large amount of power flow into the nanoslit. Furthermore, optimized parameters resulted in ~ 58.6-fold enhancement of the power flow with ~ 9.3- and 9.1-fold enhancement of the distribution of |E_x| and |E_y|, respectively. Therefore, these enhancements could be significant in understanding the role of internal corrugations in the structure. It is hoped these results are applicable to future extraordinary optical transmission systems.