Coloring fluorescence emission with silver nanowires

We demonstrate that emission from Rhodamine-6G fluorophores adsorbed on silver nanowires experiences a spectral redshift upon propagation to the distal ends of the nanowire, with the shift being proportional to the propagation distance. The end of a nanowire thus constitutes a tunable fluorescence source controlled by a single easily adjustable parameter, i.e., the position of the excitation focal spot. The effect is made possible by a combination of radiatively undamped plasmon propagation and dispersive ohmic losses in the silver nanowire. The results may be important for the development of plasmonic waveguides, fast fluorescent color switches and various nanoscale fluorescence sensors. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3355545]