  In this letter we show the inclusion of Rhodamine B molecules (RhB) inside a
dielectric-loaded surface plasmon waveguide enables for a precise determination
of its optical characteristics. The principle relies on the coupling of the
fluorescence emission of the dye to plasmonic waveguided modes allowed in of
the structure. Using leakage radiation microscopy in real and reciprocal
spaces, we measure the propagation constant of the mode and as well as their
attenuation length.
