Spin–Orbit-Engineered Selective Transport of Photons in Plasmonic Nanocircuits with Panda-Patterned Transporters

The spin–orbit coupling of light, which can be utilized to manipulate the polarization and spatial degrees of freedom of photons, has shown unprecedented potential in realizing on-chip integrated nanocircuits and quantum information processing. Particularly, this chiral coupling mechanism can result in unidirectional transport of spin-dependent light at a subwavelength scale by designing specific nanostructures. Here we propose and demonstrate a dielectric-loaded plasmonic nanocircuit with a panda-patterned transporter to directionally couple and guide plasmonic waves through two-branched waveguides. Both simulation and experimental results reveal that the waveguide modes excited by circularly polarized light with different spin states can be selectively coupled to one of two branching waveguides, with a measured unidirectionality efficiency up to 0.95. The proposed configuration may open up more possibilities in developing multifunctional nanocircuits that could be utilized for exploiting chiral manipulation with flexible degrees of freedom.