  Tightly confined plasmon waveguide modes supported by semicircular cross
section top silver nanoridges are investigated in this paper. Mode field
profiles, dispersion curves, propagation distances, confinement factors, and
figure-of-merits of semicircular top silver nanoridge plasmon waveguide mode
are calculated for different radii of curvature at different wavelengths. It is
found that semicircular top silver nanoridges support tightly confined
quasi-TEM plasmon waveguide modes. Semicircular top silver nanoridge mode has
longer propagation distance and higher figure-of-merit than that of the
cylindrical silver nanowire of the same radius of curvature.
