Effect of lower index dielectric coating on plasmon polaritons guided by finite metal stripes

The propagation properties of plasmon polaritons considering the effect of a lower index dielectric coating on metal stripe have been analyzed in this work by using a vector finite element method (FEM). The coating layer in the structure can reduce the propagation loss significantly for both symmetric and asymmetric modes without altering the 2D sub-wavelength power confinement much in the metal stripe. The effect of index contrast between coating and embedding dielectric material is also studied here for equal and unequal variation in thicknesses of coating layer in transverse plane.