We show that geometric eccentricity can be used to strongly tailor the angular radiation profiles of aluminium plasmonic bullseye antennas. High-resolution energy/momentum maps are recorded using a novel cathodoluminescence Fourier imaging technique. The angular profiles for elliptical bullseyes (ellipticity e = 0, 0.6, 0.8) are well described by a 2D dipole scattering model in which the phase and amplitude of the scattering from the bullseye grooves dictates the angular profile at a given energy. We show that geometric eccentricity is an important parameter to control the radiation profile of bullseye antennas. The new energy-momentum cathodoluminescence imaging technique can be used to map the optical properties of a wide range of dispersive and anisotropic systems, paving the way for a broad range of studies on complex nanophotonic systems.

The Netherlands Organisation for Scientific Research (NWO) , European Research Council (ERC)
ACS Photonics
Photonic Materials

Coenen, T., & Polman, A. (2019). Energy-Momentum Cathodoluminescence Imaging of Anisotropic Directionality in Elliptical Aluminium Plasmonic Bullseye Antennas. ACS Photonics, 6(2), 573–580. doi:10.1021/acsphotonics.8b01711