Longitudinal chirality, enhanced nonreciprocity, and nanoscale planar one-way plasmonic guiding

When a linear chain of plasmonic nanoparticles is exposed to a transverse dc magnetic field, the chain modes are elliptically polarized in a single plane parallel to the chain axis; hence, a new chain mode of longitudinal plasmon rotation is created. If, in addition, the chain geometry possesses longitudinal rotation, e.g., by using ellipsoidal particles that rotate in the same plane as the plasmon rotation, strong nonreciprocity is created. The structure possesses a new kind of chirality-longitudinal chirality-and supports one-way guiding. Since all particles rotate in the same plane, the geometry is planar and can be fabricated by printing leaflike patches on a single plane. Furthermore, the magnetic field is significantly weaker than in previously reported one-way guiding structures. These properties are examined for ideal (lossless) and lossy chains.