Propagating plasmon modes guided along silver metal nanoridges with triangular and inverted triangular cross sections are investigated in this paper. Mode field profiles, dispersion curves, propagation distances, and figure-of-merits of the plasmon modes are calculated for silver nanoridges with various triangular and inverted triangular waveguide cross sections. It is found that the triangular cross-section nanoridge waveguide, if designed properly, can have longer propagation distance and higher figure-of-merit than the flat-top nanoridge waveguide of the same width. When the triangle height of the nanoridge is high, the mode approaches the small angle wedge mode. An inverted triangular cross-section nanoridge mode can be considered as a hybrid mode of two metal wedge plasmon modes. When inverted triangle depth increases, the propagation distance and the figure-of-merit decrease dramatically, suggesting poorer performance when compared to the flat-top nanoridge plasmon waveguide.
© 2012 Optical Society of AmericaPDF Article