Characterization of bending losses for curved plasmonic nanowire waveguides.

We characterize bending losses of curved plasmonic nanowire waveguides for radii of curvature ranging from 1 to 12 microm and widths down to 40 nm. We use near-field measurements to separate bending losses from propagation losses. The attenuation due to bending loss is found to be as low as 0.1 microm(-1) for a curved waveguide with a width of 70 nm and a radius of curvature of 2 microm. Experimental results are supported by Finite Difference Time Domain simulations. An analytical model developed for dielectric waveguides is used to predict the trend of rising bending losses with decreasing radius of curvature in plasmonic nanowires.