The design of reconfigurable coupler based on spoof surface plasmons

The application of backward wave propagation of surface plasmon polaritons (SPPs) has recently been explored in plasmonic structures, but has not been applied to design reconfigurable coupler(s). Here, a reconfigurable spoof surface plasmon polariton (SSPP) coupler is proposed to achieve the adjustment of excitation and transmission direction of SSPPs. The dispersion of the plasmonic structure can be engineered by turning the capacitance of varactor diodes loaded on the coupler. As a result, the direction of the SSPPs transmitted on the coupler can be controlled dynamically in the same operating frequency. Experiments have confirmed that the coupler has the ability of controllable transmission direction, which illustrates that this coupler can be extended to a abroad range of applications.