We show with both experiment and calculation that highly confined surface plasmon polaritons can be efficiently excited on metallic nanowires through the process of mode transformation. One specific mode in a metallic waveguide is identified that adiabatically transforms to the confined nanowire mode as the waveguide width is reduced. Phase- and polarization-sensitive near-field investigation reveals the characteristic antisymmetric polarization nature of the mode and explains the coupling mechanism.

Phys. Rev. Lett.
Photonic Materials

Verhagen, E., Spasenović, M., Polman, A., & Kuipers, K. (2009). Nanowire plasmon excitation by adiabatic mode transformation. Phys.Rev.Lett., 102(Article number: 203904), 1–4. doi:10.1103/physrevlett.102.203904