Effect of ridge morphologies on surface plasmon scattering by subwavelength surface ridges

Surface plasmon scattering by two-dimensional ridges has been studied, mainly in the optical regime. Both the overall width and height of the ridges are fixed. The scattering properties are numerically investigated by the three-dimensional full-vector finite-difference time-domain method, with morphologies regularly changed by subdividing the width and the height of the ridges simultaneously. The results show that the transmission can be improved and the reflection reduced by increasing the degree of subdivision, which makes the surfaces of ridges much smoother. Meanwhile, morphology has little influence on the radiation, which may be attributed to the unchanged total surface area of the ridges. Moreover, we analyze the scattering of SPPs by arrays of ridges.