Orbital Angular Momentum-Controlled Tunable Directional Plasmonic Coupler

In order to realize unidirectional surface plasmon polariton coupling, here, we design an orbital angular momentum-controlled tunable directional plasmonic coupler which can distinguish optical vortex with a topological charge of +/- 1 precisely, as well as act as surface plasmon polariton propagation controller to determine the surface plasmon polariton coupling directions. The method of design for the directional plasmonic coupler is explained in detail by both the theoretical analysis and the numerical simulation showing a directionality of similar to 5:1. It is believed the directional plasmonic coupler can potentially be applied in the plasmonic control system.