Effect of surface roughness on propagation of surface plasmon polaritons along thin lossy metal films

In this paper surface plasmon polaritons (SPP) that propagate along thin lossy metal films with surface irregularities are studied. Two cases of metal slab (with infinite width) and metal strip (with finite width) are considered. Surface roughness is modelled as a grating with deterministic profile. To analyze the slab structure the method of reduced Rayleigh equation is used. The results show that antisymmetric mode is strongly affected with roughness. Accuracy of the result is demonstrated through comparisons with HFSS simulations. The effect of surface roughness on the metal strip structure is only simulated by HFSS software. It shows that the attenuation of SPP modes is increased due to the surface roughness.