Four-Port Polarization and Topological Charge Controlled Directional Plasmonic Coupler

In this letter, a four-port directional plasmonic coupler based on excited surface plasmon polariton interference is proposed, which is capable of coupling surface wave into different directions according to polarization directions and topological charges of incident light. In addition, it also acts as a light detector for both polarization and phase twist determination. It is believed that the directional plasmonic coupler will be potential in future plasmonic circuit designs and applications.