Ultrahigh efficiency plasmonic mode conversion between symmetric and antisymmetric modes in metal slab waveguides by introducing a gyration-managed waveguide link

Plasmonic mode conversion is an important topic for realizing the coupling between conventional optical and plasmonic waveguides, and between plasmonic waveguides. However, the switchable mode conversion between the symmetric and the antisymmetric modes propagating along metal slab waveguides, which are among well-known prototypes of surface plasmon polariton (SPP) modes, has never been reported, to our knowledge. In this paper, we suggested the conversion between the symmetric and the antisymmetric modes by introducing a gyration-managed metal slab waveguide link with the zero-averaged gyration. The symmetric (antisymmetric) mode can be converted to the antisymmetric (symmetric) mode with ultrahigh conversion efficiency more than $98\%$.