  We show efficient electro-optic modulation in a subwavelength gap-plasmon
waveguide (GPW) formed by an electro-optic polymer with metal coatings. The
proposed device is studied in the attenuated total reflection and end-fire
configurations. In dealing with the end-fire configuration we used a taper from
a micron sized guide to the GPW. The structure is shown to exhibit large phase
accumulation over short distances, controllable by the applied modulating
voltage.
