  Controlling the directionality of surface plasmon polaritons (SPPs) has been
widely studied, while the direction of SPPs was always switched by orthogonal
polarizations in the reported methods. Here, we present a scheme to control the
directionality of SPPs by arbitrary spin polarizations. Extremely, the device
can split two quite adjacent polarization components to two opposite
directions. The versatility of the presented design scheme can offer
opportunities for polarization sensing, polarization splitting and
polarization-controlled plasmonic devices.
