Plasmonic Nanowire Antennas: Experiment, Simulation, and Theory

• Published in: Nano letters 2010-09, Vol.10 (9), p.3596-3603
• Main Authors: Dorfmüller, Jens, Vogelgesang, Ralf, Khunsin, Worawut, Rockstuhl, Carsten, Etrich, Christoph, Kern, Klaus
• Format: Article
• Language: English
• Subjects: Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Materials science; Methods of nanofabrication; Nanocrystalline materials; Nanolithography; Nanoscale materials and structures: fabrication and characterization; Physics; Quantum wires; Surface and interface electron states
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl101921y

Recent advances in nanolithography have allowed shifting of the resonance frequency of antennas into the optical and visible wavelength range with potential applications, for example, in single molecule spectroscopy by fluorescence and directionality enhancement of molecules. Despite such great promise, the analytical means to describe the properties of optical antennas is still lacking. As the phase velocity of currents at optical frequencies in metals is much below the speed of light, standard radio frequency (RF) antenna theory does not apply directly. For the fundamental linear wire antenna, we present an analytical description that overcomes this shortage and reveals profound differences between RF and plasmonic antennas. It is fully supported by apertureless scanning near-field optical microscope measurements and finite-difference time-domain simulations. This theory is a starting point for the development of analytical models of more complex antenna structures.