Cathodoluminescence of plasmonic nanowire modes

Surface plasmon polaritons (SPPs) provide a route towards miniaturization of optical compo-nents, which has many possible applications in the field of information technology. The most basic component in guiding of signals is a wire. A gold wire is able to support SPPs, and has interesting optical properties that are not available to conventional waveguides. In this work, we study the photonic properties of gold nanowires, or nanorods, with diameter on the order of 100nmand lenghts of 350nm to severalmicrons, using cathodoluminescence (CL) spectroscopy. Nanorods or rod-like structures were fabricated using e-beam lithography, template growth and Focused Ion Beam (FIB) milling. FIB is presented as a tool for nanophotonic sample preparation and it is shown how the high resolution of the ion beam in combination with the homogeneity of a single crystal gold sample allows for fabrication of plasmonic nanostructures with unprecedented detail. Finite-difference time-domain (FDTD) simulations have been performed on nanorod geome-tries to study plasmonic modes that are supported by this configuration. It is shown that gold nanorods have organ pipe-like resonances with an an integer number of electric field antinode