Modal Properties of Hybrid Plasmonic Waveguides for Nanolaser Applications

We investigate the modal properties of nanowire-metal hybrid plasmonic waveguides by use of the coupled-mode theory and finite-element method. We show that the coupling between the nanowire fundamental HE11 mode and surface plasmon mode results in three different supermodes. We numerically calculate the dispersion relations, normalized mode areas, and confinement factors of these different modes for plasmonic nanolaser applications and show that the lowest threshold mode is determined by the waveguide geometry.