  Recently, guiding electromagnetic surface waves without sacrificing
scattering losses through paths that have arbitrary shape bumps has gained a
lot of interest due to its wealth of advantages in modern photonics and
plasmonics devices. In this study, based on transformation optics (TO)
methodology, a feasible approach to control the flow of surface plasmon
plariton (SPPs) at metal-dielectric interfaces with arbitrary curvature is
proposed. The obtained material becomes homogeneous and independent of the
bump's geometry. That is, one constant material is required to route SPP waves
without scattering the energy into the far-field region, which overcome the
bottlenecks encountered in the previous works. Several numerical simulations
are carried out to illustrate the capability of the propounded cloak to control
the SPP flows at metal/dielectric interfaces. The unique designing approach
introduced here may open a new horizon to nano-optics and downscaling of
photonic circuits.
