Mode transformation in waveguiding plasmonic structures

We study transformation of surface modes in plasmonic waveguides when the loss strength is varying from zero to realistic values. For the examples of plasmonic modes guided by cylindrical nanorod and metal-dielectric-metal slot waveguides, we show that transformation of dispersion curves follows one of two fundamental scenarios: degeneracy removal of evanescent modes and mode reconnection. We demonstrate that different parts of the same mode dispersion in lossy structures can have different origin in the lossless case