Subwavelength polarization beam splitter with controllable splitting ratio based on surface plasmon polaritons

We propose a novel V-shaped Ag nanowire structure as a subwavelength polarization beam splitter. When an incident light is focused onto the junction of the two branches, two surface plasmon polaritons (SPPs) are launched and propagate along the two branches. The polarizations of the emission light from the two ends are always parallel to the directions of the branches and the splitting ratio can be adjusted by changing the polarization of the incident light. The polarization characteristic originates from the fact that only single plasmonic waveguide mode exists in the thin nanowire and high order modes are cutoff. The near-field coupling between the two branches dominates the SPPs launching and the splitting ratio, which are very different with the single nanowire case. The V-shaped nanowire structure will have many potential applications in the integration of plasmonic devices, such as plasmonic router or polarizer.