Recently, we reported the possibility of obtaining directional scattering using a bimetallic antenna composed of closely spaced Au and Ag NPs dimers. We here first demonstrate that directional scattering can be achieved simply by using Au NP dimers made of different height. We give a first proof-of-concept that directional scattering can be used for refractive index based sensing applications. In this case, shifts of the ratio between right and left scattered light are found to happen. This effect has been used for bulk refractive index measurements and has been tested on streptavidin-biotin molecular aggregates.
Second, we designed novel nanoparticle arrangements to investigate novel plasmonic functionalities. To this purpose we designed and realized a new plasmonic oligomer structure that supports both magnetic and dark modes in the same wavelength range and study the relation between the two. Also, we investigate the unique characteristics of a photonic quasicrystal that consists of plasmonic Ag nanodisks arranged in a Penrose pattern. The quasicrystal scatters light in a complex but spectacular diffraction pattern which allowed us to assess the excitation efficiency of the various diffraction modes. Furthermore, surface plasmon polaritons can be launched almost isotropically through near-field grating coupling when the quasicrystal is positioned close to a homogeneous silver surface. It is demonstrated that the quasicristal in-coupling efficiency is dramatically enhanced compared to a nanoparticle array with the same particle density but only short-range lateral order.
Finally, a novel structure composed by gold vertical dimers has been produced. The structures support an extended hot spot, in agreement with recent literature. The resonance is tunable over the visible and IR region and both geometry and optical characteristics are easily controllable. Remarkably, we describe a preparation method which renders the hot spot region available for sensing. Advantages in terms of sensitivity are hereby discussed.